EN(w/o STI)(diag)-96
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
18.Diagnostic Procedure with Diagnostic Trouble Code (DTC)
A: DTC P000A A CAMSHAFT POSITION SLOW RESPONSE (BANK 1)
NOTE:
For the diagnostic procedure, refer to DTC P0011. <Ref. to EN(w/o STI)(diag)-99, DTC P0011 INTAKE
CAMSHAFT POSITION - TIMING OVER-ADVANCED OR SYSTEM PERFORMANCE (BANK 1), Diagnostic
Procedure with Diagnostic Trouble Code (DTC).>
B: DTC P000B B CAMSHAFT POSITION SLOW RESPONSE (BANK 1)
NOTE:
For the diagnostic procedure, refer to DTC P0014. <Ref. to EN(w/o STI)(diag)-102, DTC P0014 EXHAUST
AVCS SYSTEM 1 (RANGE/PERFORMANCE), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
C: DTC P000C A CAMSHAFT POSITION SLOW RESPONSE (BANK 2)
NOTE:
For the diagnostic procedure, refer to DTC P0021. <Ref. to EN(w/o STI)(diag)-113, DTC P0021 INTAKE
CAMSHAFT POSITION - TIMING OVER-ADVANCED OR SYSTEM PERFORMANCE (BANK 2), Diagnostic
Procedure with Diagnostic Trouble Code (DTC).>
D: DTC P000D B CAMSHAFT POSITION SLOW RESPONSE (BANK 2)
NOTE:
For the diagnostic procedure, refer to DTC P0024. <Ref. to EN(w/o STI)(diag)-116, DTC P0024 EXHAUST
AVCS SYSTEM 2 (RANGE/PERFORMANCE), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
15WRX_STI_US_EN.book 96 ペー   
EN(w/o STI)(diag)-97
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
E: DTC P0010 "A" CAMSHAFT POSITION ACTUATOR CIRCUIT/OPEN (BANK 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-15, DTC P0010 "A" CAMSHAFT POSITION ACTUA-
TOR CIRCUIT/OPEN (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 7 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Go to step 3.
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
E3B22
3
B550
215
01
B220
11
E38E37
12
E38
1
27
EN-10796
E159
1
215
E37
SBF-7
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
INTAKE
OIL CONTROL
SOLENOID LH
INTAKE
OIL CONTROL
SOLENOID RH
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 97 ペー   
EN(w/o STI)(diag)-98
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
3 CHECK POWER SUPPLY TO THE INTAKE
OIL CONTROL SOLENOID RH.
Measure the voltage between intake oil control
solenoid RH connector and engine ground.
Connector & terminal
(E38) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the power
supply circuit.
4 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID RH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM
and intake oil control solenoid RH.
3) Measure the resistance between intake oil
control solenoid RH connector and engine
ground.
Connector & terminal
(E38) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and intake oil con-
trol solenoid RH
connector.
5 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID RH CON-
NECTOR.
Measure the resistance of harness between
ECM connector and intake oil control solenoid
RH.
Connector & terminal
(E159) No. 7 — (E38) No. 2:
Is the resistance less than 1 Ω? Go to step 6. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and intake oil con-
trol solenoid RH
connector
Poor contact of
coupling connector
6 CHECK INTAKE OIL CONTROL SOLENOID
RH.
Measure the resistance between intake oil con-
trol solenoid RH terminals.
Terminals
No. 1 — No. 2:
Is the resistance 6 — 12 Ω? Repair the poor
contact of intake oil
control solenoid
RH connector.
Replace the intake
oil control solenoid
RH. <Ref. to FU(w/
o STI)-108, Oil
Control Solenoid.>
Step Check Yes No
15WRX_STI_US_EN.book 98 ペー   
EN(w/o STI)(diag)-99
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
F: DTC P0011 INTAKE CAMSHAFT POSITION - TIMING OVER-ADVANCED OR
SYSTEM PERFORMANCE (BANK 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-16, DTC P0011 INTAKE CAMSHAFT POSITION - TIM-
ING OVER-ADVANCED OR SYSTEM PERFORMANCE (BANK 1), Diagnostic Trouble Code (DTC) Detect-
ing Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 IDENTIFYING FAULTY PART.
1) Perform the Clear Memory Mode. <Ref. to
EN(w/o STI)(diag)-61, Clear Memory Mode.>
2) Replace the defective oil control solenoid by
the other (RH or LH, intake side or exhaust side)
oil control solenoid.
3) Perform appropriate drive cycle test. <Ref.
to EN(w/o STI)(diag)-50, Drive Cycle.>
4) Make sure that the fault occurrence (DTC
and incorrect advancing) has shifted to the
other location.
Did the detected DTC shift to
the location where the oil con-
trol solenoid was replaced?
Replace the faulty
oil control sole-
noid.
Go to step 2.
2 CHECK CURRENT DATA.
1) Start the engine and let it idle.
2) Read the value of «VVT Adv. Ang. Amount
R» using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
Is the value of «VVT Adv. Ang.
Amount R» approx. 0 deg?
Go to step 3. Check the follow-
ing item and repair
or replace if neces-
sary.
Intake cam
sprocket (clog or
dirt of oil routing,
setting of spring)
Intake camshaft
(dirt, damage of
camshaft)
3 CHECK CURRENT DATA.
1) Drive with acceleration and deceleration at
80 km/h (50 MPH) or less.
NOTE:
Drive to an extent that the duty output of oil flow
control solenoid valve increases.
2) Read the values of «OCV Duty R» and
«VVT Adv. Ang. Amount R» using the Subaru
Select Monitor.
NOTE:
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
When the value of «OCV Duty
R» increases more than 10%,
is the value of «VVT Adv. Ang.
Amount R» approx. 0 deg?
Check the follow-
ing item and repair
or replace if neces-
sary.
Intake cam
sprocket (clog or
dirt of oil routing,
setting of spring)
Intake camshaft
(dirt, damage of
camshaft)
Perform the follow-
ing procedures,
and clean the oil
routing.
Replace the
engine oil and idle
the engine for 5
minutes, and then
replace the oil filter
and engine oil.
<Ref. to LU(w/o
STI)-11,
REPLACEMENT,
Engine Oil.> <Ref.
to LU(w/o STI)-53,
Engine Oil Filter.>
15WRX_STI_US_EN.book 99 ペー   
EN(w/o STI)(diag)-100
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
G: DTC P0013 B CAMSHAFT POSITION ACTUATOR CIRCUIT/OPEN (BANK 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-18, DTC P0013 B CAMSHAFT POSITION ACTUATOR
CIRCUIT/OPEN (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 23 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Go to step 3.
ECM
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
E3B22
3
B550
215
01
B220
11
E66E63
12
E63
1
223
EN-10795
E159
1
231
E66
SBF-7
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
EXHAUST
OIL CONTROL
SOLENOID LH
EXHAUST
OIL CONTROL
SOLENOID RH
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 100 ージ 20  
EN(w/o STI)(diag)-101
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
3 CHECK POWER SUPPLY TO THE EXHAUST
OIL CONTROL SOLENOID RH.
Measure the voltage between exhaust oil con-
trol solenoid RH connector and engine ground.
Connector & terminal
(E63) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the power
supply circuit.
4 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID RH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
exhaust oil control solenoid RH.
3) Measure the resistance between exhaust oil
control solenoid RH connector and engine
ground.
Connector & terminal
(E63) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and exhaust oil
control solenoid
RH connector.
5 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID RH CON-
NECTOR.
Measure the resistance of harness between
ECM connector and exhaust oil control solenoid
RH.
Connector & terminal
(E159) No. 23 — (E63) No. 2:
Is the resistance less than 1 Ω? Go to step 6. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and exhaust oil
control solenoid
RH connector
Poor contact of
coupling connector
6 CHECK EXHAUST OIL CONTROL SOLE-
NOID RH.
Measure the resistance between exhaust oil
control solenoid RH terminals.
Terminals
No. 1 — No. 2:
Is the resistance 6 — 12 Ω? Repair the poor
contact of exhaust
oil control solenoid
RH connector.
Replace the
exhaust oil control
solenoid RH. <Ref.
to FU(w/o STI)-
108, Oil Control
Solenoid.>
Step Check Yes No
15WRX_STI_US_EN.book 101 ージ 20  
EN(w/o STI)(diag)-102
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
H: DTC P0014 EXHAUST AVCS SYSTEM 1 (RANGE/PERFORMANCE)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-19, DTC P0014 EXHAUST AVCS SYSTEM 1 (RANGE/
PERFORMANCE), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 IDENTIFYING FAULTY PART.
1) Perform the Clear Memory Mode. <Ref. to
EN(w/o STI)(diag)-61, Clear Memory Mode.>
2) Replace the defective oil control solenoid by
the other (RH or LH, intake side or exhaust side)
oil control solenoid.
3) Perform appropriate drive cycle test. <Ref.
to EN(w/o STI)(diag)-50, Drive Cycle.>
4) Make sure that the fault occurrence (DTC
and incorrect advancing) has shifted to the
other location.
Did the detected DTC shift to
the location where the oil con-
trol solenoid was replaced?
Replace the faulty
oil control sole-
noid.
Go to step 2.
2 CHECK CURRENT DATA.
1) Start the engine and let it idle.
2) Read the value of «Exh. VVT Retard Ang.
R» using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
Is the value of «Exh. VVT
Retard Ang. R» approx. 0 deg?
Go to step 3. Check the follow-
ing item and repair
or replace if neces-
sary.
Exhaust cam
sprocket (clog or
dirt of oil routing,
setting of spring)
Exhaust cam-
shaft (dirt, dam-
age of camshaft)
3 CHECK CURRENT DATA.
1) Drive with acceleration and deceleration at
80 km/h (50 MPH) or less.
NOTE:
Drive to an extent that the duty output of oil flow
control solenoid valve increases.
2) Read the values of «Exh. OCV Duty R» and
«Exh. VVT Retard Ang. R» using the Subaru
Select Monitor.
NOTE:
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
When the value of «Exh. OCV
Duty R» increases more than
10%, is the value of «Exh. VVT
Retard Ang. R» approx. 0 deg?
Check the follow-
ing item and repair
or replace if neces-
sary.
Exhaust cam
sprocket (clog or
dirt of oil routing,
setting of spring)
Exhaust cam-
shaft (dirt, dam-
age of camshaft)
Perform the follow-
ing procedures,
and clean the oil
routing.
Replace the
engine oil and idle
the engine for 5
minutes, and then
replace the oil filter
and engine oil.
<Ref. to LU(w/o
STI)-11,
REPLACEMENT,
Engine Oil.> <Ref.
to LU(w/o STI)-53,
Engine Oil Filter.>
15WRX_STI_US_EN.book 102 ージ 20  
EN(w/o STI)(diag)-103
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
I: DTC P0016 CRANKSHAFT POSITION - CAMSHAFT POSITION CORRELA-
TION (BANK1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-20, DTC P0016 CRANKSHAFT POSITION - CAM-
SHAFT POSITION CORRELATION (BANK1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is DTC other than P0016,
P0017, P0018 or P0019 dis-
played?
Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK INTAKE OIL CONTROL SOLENOID
RH.
Check the intake oil control solenoid RH. <Ref.
to FU(w/o STI)-110, INSPECTION, Oil Control
Solenoid.>
Is the intake oil control solenoid
RH normal?
Go to step 3. Replace the intake
oil control solenoid
RH. <Ref. to FU(w/
o STI)-108, Oil
Control Solenoid.>
3 CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Using ST and by turning the crankshaft, align
the alignment marks of crank sprocket, intake
cam sprocket and exhaust cam sprocket. <Ref.
to ME(w/o STI)-116, Timing Chain Assembly.>
ST 18252AA000 CRANKSHAFT
SOCKET
Is the timing chain installed in
the proper position?
Go to step 4. Correct the instal-
lation condition of
timing chain. <Ref.
to ME(w/o STI)-
116, Timing Chain
Assembly.>
4 CHECK CAM CARRIER FILTER.
Check the filter installed to the cam carrier.
<Ref. to ME(w/o STI)-209, INSPECTION, Cam
Carrier.>
Is the cam carrier filter normal? Replace the intake
cam sprocket RH.
<Ref. to ME(w/o
STI)-141, Cam
Sprocket.> After
the operation is
complete, go to the
next step. Go to
step 5.
Replace the cam
carrier filter. <Ref.
to ME(w/o STI)-
172, Cam Carrier.>
15WRX_STI_US_EN.book 103 ージ 20  
EN(w/o STI)(diag)-104
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
5 CHECK CURRENT DATA.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, OPERATION, Clear Memory
Mode.>
2) Start the engine and warm up completely.
3) Using the Subaru Select Monitor, read the
values of «VVT Initial Position Learning Value
#1» and «VVT Adv. Ang. Amount R» while the
vehicle is in stable condition for 30 seconds or
more with the engine idling.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
4) Calculate the values using the following for-
mula. Ignore the unit at this time.
|«VVT Initial Position Learning Value #1» – (60
+ «VVT Adv. Ang. Amount R»)|
Is the calculation result less
than 10?
Go to step 6. Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
6 CHECK DTC.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, OPERATION, Clear Memory
Mode.>
2) Perform drive cycle N. <Ref. to EN(w/o
STI)(diag)-59, DRIVE CYCLE N, PROCE-
DURE, Drive Cycle.>
Is the same DTC as current
diagnosis output?
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
End.
Step Check Yes No
15WRX_STI_US_EN.book 104 ージ 20  
EN(w/o STI)(diag)-105
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
J: DTC P0017 CRANK AND CAM TIMING B SYSTEM FAILURE (BANK 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-21, DTC P0017 CRANK AND CAM TIMING B SYSTEM
FAILURE (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is DTC other than P0016,
P0017, P0018 or P0019 dis-
played?
Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK EXHAUST OIL CONTROL SOLE-
NOID RH.
Check the exhaust oil control solenoid RH.
<Ref. to FU(w/o STI)-110, INSPECTION, Oil
Control Solenoid.>
Is the exhaust oil control sole-
noid RH normal?
Go to step 3. Replace the
exhaust oil control
solenoid RH. <Ref.
to FU(w/o STI)-
108, Oil Control
Solenoid.>
3 CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Using ST and by turning the crankshaft, align
the alignment marks of crank sprocket, intake
cam sprocket and exhaust cam sprocket. <Ref.
to ME(w/o STI)-116, Timing Chain Assembly.>
ST 18252AA000 CRANKSHAFT
SOCKET
Is the timing chain installed in
the proper position?
Go to step 4. Correct the instal-
lation condition of
timing chain. <Ref.
to ME(w/o STI)-
116, Timing Chain
Assembly.>
4 CHECK CAM CARRIER FILTER.
Check the filter installed to the cam carrier.
<Ref. to ME(w/o STI)-209, INSPECTION, Cam
Carrier.>
Is the cam carrier filter normal? Replace the
exhaust cam
sprocket RH. <Ref.
to ME(w/o STI)-
141, Cam
Sprocket.> After
the operation is
complete, go to the
next step. Go to
step 5.
Replace the cam
carrier filter. <Ref.
to ME(w/o STI)-
172, Cam Carrier.>
15WRX_STI_US_EN.book 105 ージ 20  
EN(w/o STI)(diag)-106
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
5 CHECK CURRENT DATA.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, OPERATION, Clear Memory
Mode.>
2) Start the engine and warm up completely.
3) Using the Subaru Select Monitor, read the
values of «VVT Ex Initial Position Learning
Value #1» and «Exh. VVT Retard Ang. R» while
the vehicle is in stable condition for 30 seconds
or more with the engine idling.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
4) Calculate the values using the following for-
mula. Ignore the unit at this time.
|«VVT Ex Initial Position Learning Value #1» –
(90 – «Exh. VVT Retard Ang. R»)|
Is the calculation result less
than 10?
Go to step 6. Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
6 CHECK DTC.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, OPERATION, Clear Memory
Mode.>
2) Perform drive cycle N. <Ref. to EN(w/o
STI)(diag)-59, DRIVE CYCLE N, PROCE-
DURE, Drive Cycle.>
Is the same DTC as current
diagnosis output?
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
End.
Step Check Yes No
15WRX_STI_US_EN.book 106 ージ 20  
EN(w/o STI)(diag)-107
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
K: DTC P0018 CRANKSHAFT POSITION - CAMSHAFT POSITION CORRELA-
TION (BANK2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-22, DTC P0018 CRANKSHAFT POSITION - CAM-
SHAFT POSITION CORRELATION (BANK2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is DTC other than P0016,
P0017, P0018 or P0019 dis-
played?
Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK INTAKE OIL CONTROL SOLENOID
LH.
Check the intake oil control solenoid LH. <Ref.
to FU(w/o STI)-110, INSPECTION, Oil Control
Solenoid.>
Is the intake oil control solenoid
LH normal?
Go to step 3. Replace the intake
oil control solenoid
LH. <Ref. to FU(w/
o STI)-108, Oil
Control Solenoid.>
3 CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Using ST and by turning the crankshaft, align
the alignment marks of crank sprocket, intake
cam sprocket and exhaust cam sprocket. <Ref.
to ME(w/o STI)-116, Timing Chain Assembly.>
ST 18252AA000 CRANKSHAFT
SOCKET
Is the timing chain installed in
the proper position?
Go to step 4. Correct the instal-
lation condition of
timing chain. <Ref.
to ME(w/o STI)-
116, Timing Chain
Assembly.>
4 CHECK CAM CARRIER FILTER.
Check the filter installed to the cam carrier.
<Ref. to ME(w/o STI)-209, INSPECTION, Cam
Carrier.>
Is the cam carrier filter normal? Replace the intake
cam sprocket LH.
<Ref. to ME(w/o
STI)-141, Cam
Sprocket.> After
the operation is
complete, go to the
next step. Go to
step 5.
Replace the cam
carrier filter. <Ref.
to ME(w/o STI)-
172, Cam Carrier.>
15WRX_STI_US_EN.book 107 ージ 20  
EN(w/o STI)(diag)-108
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
5 CHECK CURRENT DATA.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, OPERATION, Clear Memory
Mode.>
2) Start the engine and warm up completely.
3) Using the Subaru Select Monitor, read the
values of «VVT Initial Position Learning Value
#2» and «VVT Adv. Ang. Amount L» while the
vehicle is in stable condition for 30 seconds or
more with the engine idling.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
4) Calculate the values using the following for-
mula. Ignore the unit at this time.
|«VVT Initial Position Learning Value #2» – (60
+ «VVT Adv. Ang. Amount L»)|
Is the calculation result less
than 10?
Go to step 6. Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
6 CHECK DTC.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, OPERATION, Clear Memory
Mode.>
2) Perform drive cycle N. <Ref. to EN(w/o
STI)(diag)-59, DRIVE CYCLE N, PROCE-
DURE, Drive Cycle.>
Is the same DTC as current
diagnosis output?
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
End.
Step Check Yes No
15WRX_STI_US_EN.book 108 ージ 20  
EN(w/o STI)(diag)-109
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
L: DTC P0019 CRANK AND CAM TIMING B SYSTEM FAILURE (BANK 2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-22, DTC P0019 CRANK AND CAM TIMING B SYSTEM
FAILURE (BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is DTC other than P0016,
P0017, P0018 or P0019 dis-
played?
Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK EXHAUST OIL CONTROL SOLE-
NOID LH.
Check the exhaust oil control solenoid LH.
<Ref. to FU(w/o STI)-110, INSPECTION, Oil
Control Solenoid.>
Is the exhaust oil control sole-
noid LH normal?
Go to step 3. Replace the
exhaust oil control
solenoid LH. <Ref.
to FU(w/o STI)-
108, Oil Control
Solenoid.>
3 CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Using ST and by turning the crankshaft, align
the alignment marks of crank sprocket, intake
cam sprocket and exhaust cam sprocket. <Ref.
to ME(w/o STI)-116, Timing Chain Assembly.>
ST 18252AA000 CRANKSHAFT
SOCKET
Is the timing chain installed in
the proper position?
Go to step 4. Correct the instal-
lation condition of
timing chain. <Ref.
to ME(w/o STI)-
116, Timing Chain
Assembly.>
4 CHECK CAM CARRIER FILTER.
Check the filter installed to the cam carrier.
<Ref. to ME(w/o STI)-209, INSPECTION, Cam
Carrier.>
Is the cam carrier filter normal? Replace the
exhaust cam
sprocket LH. <Ref.
to ME(w/o STI)-
141, Cam
Sprocket.> After
the operation is
complete, go to the
next step. Go to
step 5.
Replace the cam
carrier filter. <Ref.
to ME(w/o STI)-
172, Cam Carrier.>
15WRX_STI_US_EN.book 109 ージ 20  
EN(w/o STI)(diag)-110
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
5 CHECK CURRENT DATA.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, OPERATION, Clear Memory
Mode.>
2) Start the engine and warm up completely.
3) Using the Subaru Select Monitor, read the
values of «VVT Ex Initial Position Learning
Value #2» and «Exh. VVT Retard Ang. L» while
the vehicle is in stable condition for 30 seconds
or more with the engine idling.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
4) Calculate the values using the following for-
mula. Ignore the unit at this time.
|«VVT Ex Initial Position Learning Value #2» –
(90 – «Exh. VVT Retard Ang. L»)|
Is the calculation result less
than 10?
Go to step 6. Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
6 CHECK DTC.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, OPERATION, Clear Memory
Mode.>
2) Perform drive cycle N. <Ref. to EN(w/o
STI)(diag)-59, DRIVE CYCLE N, PROCE-
DURE, Drive Cycle.>
Is the same DTC as current
diagnosis output?
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
End.
Step Check Yes No
15WRX_STI_US_EN.book 110 ージ 20  
EN(w/o STI)(diag)-111
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
M: DTC P0020 "A" CAMSHAFT POSITION ACTUATOR CIRCUIT/OPEN (BANK 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-22, DTC P0020 "A" CAMSHAFT POSITION ACTUA-
TOR CIRCUIT/OPEN (BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 15 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Go to step 3.
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
E3B22
3
B550
215
01
B220
11
E38E37
12
E38
1
27
EN-10796
E159
1
215
E37
SBF-7
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
INTAKE
OIL CONTROL
SOLENOID LH
INTAKE
OIL CONTROL
SOLENOID RH
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 111 ージ 20  
EN(w/o STI)(diag)-112
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
3 CHECK POWER SUPPLY TO THE INTAKE
OIL CONTROL SOLENOID LH.
Measure the voltage between intake oil control
solenoid LH connector and engine ground.
Connector & terminal
(E37) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the power
supply circuit.
4 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID LH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
intake oil control solenoid LH.
3) Measure the resistance between intake oil
control solenoid LH connector and engine
ground.
Connector & terminal
(E37) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and intake oil con-
trol solenoid LH
connector.
5 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID LH CON-
NECTOR.
Measure the resistance of harness between
ECM connector and intake oil control solenoid
LH.
Connector & terminal
(E159) No. 15 — (E37) No. 2:
Is the resistance less than 1 Ω? Go to step 6. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and intake oil con-
trol solenoid LH
connector
Poor contact of
coupling connector
6 CHECK INTAKE OIL CONTROL SOLENOID
LH.
Measure the resistance between intake oil con-
trol solenoid LH terminals.
Terminals
No. 1 — No. 2:
Is the resistance 6 — 12 Ω? Repair the poor
contact of intake oil
control solenoid
LH connector.
Replace the intake
oil control solenoid
LH. <Ref. to FU(w/
o STI)-108, Oil
Control Solenoid.>
Step Check Yes No
15WRX_STI_US_EN.book 112 ージ 20  
EN(w/o STI)(diag)-113
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
N: DTC P0021 INTAKE CAMSHAFT POSITION - TIMING OVER-ADVANCED OR
SYSTEM PERFORMANCE (BANK 2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-22, DTC P0021 INTAKE CAMSHAFT POSITION - TIM-
ING OVER-ADVANCED OR SYSTEM PERFORMANCE (BANK 2), Diagnostic Trouble Code (DTC) Detect-
ing Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 IDENTIFYING FAULTY PART.
1) Perform the Clear Memory Mode. <Ref. to
EN(w/o STI)(diag)-61, Clear Memory Mode.>
2) Replace the defective oil control solenoid by
the other (RH or LH, intake side or exhaust side)
oil control solenoid.
3) Perform appropriate drive cycle test. <Ref.
to EN(w/o STI)(diag)-50, Drive Cycle.>
4) Make sure that the fault occurrence (DTC
and incorrect advancing) has shifted to the
other location.
Did the detected DTC shift to
the location where the oil con-
trol solenoid was replaced?
Replace the faulty
oil control sole-
noid.
Go to step 2.
2 CHECK CURRENT DATA.
1) Start the engine and let it idle.
2) Read the value of «VVT Adv. Ang. Amount
L» using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
Is the value of «VVT Adv. Ang.
Amount L» approx. 0 deg?
Go to step 3. Check the follow-
ing item and repair
or replace if neces-
sary.
Intake cam
sprocket (clog or
dirt of oil routing,
setting of spring)
Intake camshaft
(dirt, damage of
camshaft)
3 CHECK CURRENT DATA.
1) Drive with acceleration and deceleration at
80 km/h (50 MPH) or less.
NOTE:
Drive to an extent that the duty output of oil flow
control solenoid valve increases.
2) Read the values of «OCV Duty L» and «VVT
Adv. Ang. Amount L» using the Subaru Select
Monitor.
NOTE:
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
When the value of «OCV Duty
L» increases more than 10%, is
the value of «VVT Adv. Ang.
Amount L» approx. 0 deg?
Check the follow-
ing item and repair
or replace if neces-
sary.
Intake cam
sprocket (clog or
dirt of oil routing,
setting of spring)
Intake camshaft
(dirt, damage of
camshaft)
Perform the follow-
ing procedures,
and clean the oil
routing.
Replace the
engine oil and idle
the engine for 5
minutes, and then
replace the oil filter
and engine oil.
<Ref. to LU(w/o
STI)-11,
REPLACEMENT,
Engine Oil.> <Ref.
to LU(w/o STI)-53,
Engine Oil Filter.>
15WRX_STI_US_EN.book 113 ージ 20  
EN(w/o STI)(diag)-114
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
O: DTC P0023 B CAMSHAFT POSITION ACTUATOR CIRCUIT/OPEN (BANK 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-22, DTC P0023 B CAMSHAFT POSITION ACTUATOR
CIRCUIT/OPEN (BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 31 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Go to step 3.
ECM
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
E3B22
3
B550
215
01
B220
11
E66E63
12
E63
1
223
EN-10795
E159
1
231
E66
SBF-7
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
EXHAUST
OIL CONTROL
SOLENOID LH
EXHAUST
OIL CONTROL
SOLENOID RH
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 114 ージ 20  
EN(w/o STI)(diag)-115
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
3 CHECK POWER SUPPLY TO THE EXHAUST
OIL CONTROL SOLENOID LH.
Measure the voltage between exhaust oil con-
trol solenoid LH connector and engine ground.
Connector & terminal
(E66) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the power
supply circuit.
4 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID LH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
exhaust oil control solenoid LH.
3) Measure the resistance between exhaust oil
control solenoid LH connector and engine
ground.
Connector & terminal
(E66) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and exhaust oil
control solenoid
LH connector.
5 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID LH CON-
NECTOR.
Measure the resistance of harness between
ECM connector and exhaust oil control solenoid
LH.
Connector & terminal
(E159) No. 31 — (E66) No. 2:
Is the resistance less than 1 Ω? Go to step 6. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and exhaust oil
control solenoid
LH connector
Poor contact of
coupling connector
6 CHECK EXHAUST OIL CONTROL SOLE-
NOID LH.
Measure the resistance between exhaust oil
control solenoid LH terminals.
Terminals
No. 1 — No. 2:
Is the resistance 6 — 12 Ω? Repair the poor
contact of exhaust
oil control solenoid
LH connector.
Replace the
exhaust oil control
solenoid LH. <Ref.
to FU(w/o STI)-
108, Oil Control
Solenoid.>
Step Check Yes No
15WRX_STI_US_EN.book 115 ージ 20  
EN(w/o STI)(diag)-116
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
P: DTC P0024 EXHAUST AVCS SYSTEM 2 (RANGE/PERFORMANCE)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-22, DTC P0024 EXHAUST AVCS SYSTEM 2 (RANGE/
PERFORMANCE), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 IDENTIFYING FAULTY PART.
1) Perform the Clear Memory Mode. <Ref. to
EN(w/o STI)(diag)-61, Clear Memory Mode.>
2) Replace the defective oil control solenoid by
the other (RH or LH, intake side or exhaust side)
oil control solenoid.
3) Perform appropriate drive cycle test. <Ref.
to EN(w/o STI)(diag)-50, Drive Cycle.>
4) Make sure that the fault occurrence (DTC
and incorrect advancing) has shifted to the
other location.
Did the detected DTC shift to
the location where the oil con-
trol solenoid was replaced?
Replace the faulty
oil control sole-
noid.
Go to step 2.
2 CHECK CURRENT DATA.
1) Start the engine and let it idle.
2) Read the value of «Exh. VVT Retard Ang.
L» using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
Is the value of «Exh. VVT
Retard Ang. L» approx. 0 deg?
Go to step 3. Check the follow-
ing item and repair
or replace if neces-
sary.
Exhaust cam
sprocket (clog or
dirt of oil routing,
setting of spring)
Exhaust cam-
shaft (dirt, dam-
age of camshaft)
3 CHECK CURRENT DATA.
1) Drive with acceleration and deceleration at
80 km/h (50 MPH) or less.
NOTE:
Drive to an extent that the duty output of oil flow
control solenoid valve increases.
2) Read the values of «Exh. OCV Duty L» and
«Exh. VVT Retard Ang. L» using the Subaru
Select Monitor.
NOTE:
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
When the value of «Exh. OCV
Duty L» increases more than
10%, is the value of «Exh. VVT
Retard Ang. L» approx. 0 deg?
Check the follow-
ing item and repair
or replace if neces-
sary.
Exhaust cam
sprocket (clog or
dirt of oil routing,
setting of spring)
Exhaust cam-
shaft (dirt, dam-
age of camshaft)
Perform the follow-
ing procedures,
and clean the oil
routing.
Replace the
engine oil and idle
the engine for 5
minutes, and then
replace the oil filter
and engine oil.
<Ref. to LU(w/o
STI)-11,
REPLACEMENT,
Engine Oil.> <Ref.
to LU(w/o STI)-53,
Engine Oil Filter.>
15WRX_STI_US_EN.book 116 ージ 20  
EN(w/o STI)(diag)-117
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Q: DTC P0030 HO2S HEATER CONTROL CIRCUIT (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-22, DTC P0030 HO2S HEATER CONTROL CIRCUIT
(BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 117 ージ 20  
EN(w/o STI)(diag)-118
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Start and warm up the engine.
2) Turn the ignition switch to OFF.
3) Disconnect the connectors from ECM and
front oxygen (A/F) sensor.
4) Measure the resistance of harness between
ECM connector and front oxygen (A/F) sensor
connector.
Connector & terminal
(E158) No. 15 — (E24) No. 1:
(E159) No. 9 — (E24) No. 2:
(E158) No. 27 — (E24) No. 4:
(E158) No. 39 — (E24) No. 5:
Is the resistance less than 1 Ω? Go to step 2. Repair the open
circuit of harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
2 CHECK FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between front oxygen
(A/F) sensor terminals.
Terminals
No. 2 — No. 3:
Is the resistance 2 — 3 Ω? Go to step 3. Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
3 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and front oxygen
(A/F) sensor connector.
Is there poor contact of ECM or
front oxygen (A/F) sensor con-
nector?
Repair the poor
contact of ECM or
front oxygen (A/F)
sensor connector.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
15WRX_STI_US_EN.book 118 ージ 20  
EN(w/o STI)(diag)-119
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
R: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-24, DTC P0031 HO2S HEATER CONTROL CIRCUIT
LOW (BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 119 ージ 20  
EN(w/o STI)(diag)-120
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK POWER SUPPLY TO FRONT OXY-
GEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from front oxy-
gen (A/F) sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between front oxygen
(A/F) sensor connector and engine ground.
Connector & terminal
(E24) No. 3 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the power
supply line.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
A/F, oxygen sen-
sor relay and front
oxygen (A/F) sen-
sor connector
Poor contact of
A/F, oxygen sen-
sor relay connector
Poor contact of
coupling connector
Malfunction of A/
F, oxygen sensor
relay
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and front oxygen (A/F) sensor connector.
Connector & terminal
(E24) No. 2 — (E159) No. 9:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit of harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
3 CHECK GROUND CIRCUIT FOR ECM.
Measure the resistance of harness between
ECM connector and engine ground.
Connector & terminal
(B134) No. 35 — Engine ground:
(B134) No. 47 — Engine ground:
(E159) No. 10 — Engine ground:
(E159) No. 17 — Engine ground:
(E159) No. 18 — Engine ground:
(E159) No. 25 — Engine ground:
(E159) No. 26 — Engine ground:
Is the resistance less than 5 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
coupling connector
4 CHECK FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between front oxygen
(A/F) sensor terminals.
Terminals
No. 2 — No. 3:
Is the resistance 2 — 3 Ω? Repair the poor
contact of ECM
connector.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
15WRX_STI_US_EN.book 120 ージ 20  
EN(w/o STI)(diag)-121
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
S: DTC P0032 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-25, DTC P0032 HO2S HEATER CONTROL CIRCUIT
HIGH (BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 121 ージ 20  
EN(w/o STI)(diag)-122
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 9 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
Go to step 2.
2 CHECK GROUND CIRCUIT FOR ECM.
1) Disconnect the connector from ECM.
2) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(B134) No. 35 — Engine ground:
(B134) No. 47 — Engine ground:
(E159) No. 10 — Engine ground:
(E159) No. 17 — Engine ground:
(E159) No. 18 — Engine ground:
(E159) No. 25 — Engine ground:
(E159) No. 26 — Engine ground:
Is the resistance less than 5 Ω? Repair the poor
contact of ECM
connector.
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
coupling connector
15WRX_STI_US_EN.book 122 ージ 20  
EN(w/o STI)(diag)-123
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
T: DTC P0037 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-26, DTC P0037 HO2S HEATER CONTROL CIRCUIT
LOW (BANK 1 SENSOR 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 123 ージ 20  
EN(w/o STI)(diag)-124
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK POWER SUPPLY TO REAR OXY-
GEN SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear oxygen
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between rear oxygen
sensor connector and engine ground.
Connector & terminal
(E25) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the power
supply line.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
A/F, oxygen sen-
sor relay and rear
oxygen sensor
connector
Poor contact of
A/F, oxygen sen-
sor relay connector
Poor contact of
coupling connector
Malfunction of A/
F, oxygen sensor
relay
2 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and rear oxygen sensor connector.
Connector & terminal
(E25) No. 2 — (E159) No. 3:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit of harness
between ECM con-
nector and rear
oxygen sensor
connector.
3 CHECK GROUND CIRCUIT FOR ECM.
Measure the resistance of harness between
ECM connector and engine ground.
Connector & terminal
(B134) No. 35 — Engine ground:
(B134) No. 47 — Engine ground:
(E159) No. 10 — Engine ground:
(E159) No. 17 — Engine ground:
(E159) No. 18 — Engine ground:
(E159) No. 25 — Engine ground:
(E159) No. 26 — Engine ground:
Is the resistance less than 5 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
coupling connector
4 CHECK REAR OXYGEN SENSOR.
Measure the resistance between rear oxygen
sensor connector terminals.
Terminals
No. 1 — No. 2:
Is the resistance 5 — 7 Ω? Repair the poor
contact of ECM
connector.
Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
15WRX_STI_US_EN.book 124 ージ 20  
EN(w/o STI)(diag)-125
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
U: DTC P0038 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-27, DTC P0038 HO2S HEATER CONTROL CIRCUIT
HIGH (BANK 1 SENSOR 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 125 ージ 20  
EN(w/o STI)(diag)-126
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 3 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and rear
oxygen sensor
connector.
Go to step 2.
2 CHECK GROUND CIRCUIT FOR ECM.
1) Disconnect the connector from ECM.
2) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(B134) No. 35 — Engine ground:
(B134) No. 47 — Engine ground:
(E159) No. 10 — Engine ground:
(E159) No. 17 — Engine ground:
(E159) No. 18 — Engine ground:
(E159) No. 25 — Engine ground:
(E159) No. 26 — Engine ground:
Is the resistance less than 5 Ω? Repair the poor
contact of ECM
connector.
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
coupling connector
15WRX_STI_US_EN.book 126 ージ 20  
EN(w/o STI)(diag)-127
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
V: DTC P0068 MAP/MAF - THROTTLE POSITION CORRELATION
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-28, DTC P0068 MAP/MAF - THROTTLE POSITION
CORRELATION, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK AIR INTAKE SYSTEM. Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
Go to step 2.
2 CHECK MANIFOLD ABSOLUTE PRESSURE
AND INTAKE AIR TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Using the Subaru Select Monitor or a gen-
eral scan tool, read the value in «Mani. Absolute
Pressure».
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
“General Scan Tool Instruction Manual”.
Is the value in «Mani. Absolute
Pressure» 73.3 — 106.6 kPa
(550 — 800 mmHg, 21.65 —
31.50 inHg) when the ignition is
turned ON, and 20.0 — 46.7
kPa (150 — 350 mmHg, 5.91 —
13.78 inHg) during idling?
Go to step 3. Replace the mani-
fold absolute pres-
sure and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-120, Mani-
fold Absolute Pres-
sure and Intake Air
Temperature Sen-
sor.>
3 CHECK THROTTLE OPENING ANGLE.
Using the Subaru Select Monitor or a general
scan tool, read the value in «Throttle Opening
Angle».
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
“General Scan Tool Instruction Manual”.
Is the value in «Throttle Open-
ing Angle» with the throttle fully
closed less than 5%?
Go to step 4. Replace the elec-
tronic throttle con-
trol. <Ref. to FU(w/
o STI)-15, Throttle
Body.>
4 CHECK THROTTLE OPENING ANGLE. Is the value in «Throttle Open-
ing Angle» with the throttle fully
open 85% or more?
Replace the mani-
fold absolute pres-
sure and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-120, Mani-
fold Absolute Pres-
sure and Intake Air
Temperature Sen-
sor.>
Replace the elec-
tronic throttle con-
trol. <Ref. to FU(w/
o STI)-15, Throttle
Body.>
15WRX_STI_US_EN.book 127 ージ 20  
EN(w/o STI)(diag)-128
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
W: DTC P0071 AMBIENT TEMPERATURE SENSOR CIRCUIT "A" RANGE/PER-
FORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-30, DTC P0071 AMBIENT TEMPERATURE SENSOR
CIRCUIT "A" RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK CURRENT DATA.
1) Turn the ignition switch to ON.
2) Read the value of «Ambient Air Tempera-
ture» using the Subaru Select Monitor or a gen-
eral scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For HVAC System”.
<Ref. to AC(diag)-40, Read Current Data.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
3) Read the change of the value in «Ambient
Air Temperature» while heating and cooling the
ambient sensor using a hair dryer.
CAUTION:
Do not heat the part to the temperature
where you cannot touch it with your bare
hand in order to prevent burning yourself
and protect the part.
Does the value of «Ambient Air
Temperature» change between
heating and cooling?
Repair the poor
contact of ECM
connector.
Replace the ambi-
ent sensor. <Ref.
to AC-72, Ambient
Sensor.>
15WRX_STI_US_EN.book 128 ージ 20  
EN(w/o STI)(diag)-129
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
X: DTC P0072 AMBIENT TEMPERATURE SENSOR CIRCUIT "A" LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-32, DTC P0072 AMBIENT TEMPERATURE SENSOR
CIRCUIT "A" LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
Y: DTC P0073 AMBIENT TEMPERATURE SENSOR CIRCUIT "A" HIGH
NOTE:
For the diagnostic procedure, refer to DTC P0072. <Ref. to EN(w/o STI)(diag)-129, DTC P0072 AMBIENT
TEMPERATURE SENSOR CIRCUIT "A" LOW, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
Step Check Yes No
1 CHECK DTC.
Check for DTC. <Ref. to EN(w/o STI)(diag)-46,
Read Diagnostic Trouble Code (DTC).>
Is P0072 or P0073 displayed in
«Present fault»?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK COMBINATION METER.
Check the combination meter system. <Ref. to
IDI(diag)-2, Basic Diagnostic Procedure.>
Is the combination meter sys-
tem normal?
Repair the poor
contact of ECM
connector.
Repair the combi-
nation meter sys-
tem. <Ref. to
IDI(diag)-2, Basic
Diagnostic Proce-
dure.>
15WRX_STI_US_EN.book 129 ージ 20  
EN(w/o STI)(diag)-130
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Z: DTC P0087 FUEL RAIL/SYSTEM PRESSURE - TOO LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-33, DTC P0087 FUEL RAIL/SYSTEM PRESSURE -
TOO LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
Poor acceleration
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR FUEL DELIVERY LINE LEAK-
AGE.
Visually check the fuel delivery line for leakage.
WARNING:
When checking fuel delivery line during
engine operation, be very careful so that
one's hair, body and clothes do not touch
the rotating part in the engine compartment.
If there is fuel leakage, the fuel can be
combusted spontaneously by the engine
heat, resulting in serious accident. There-
fore, take extra care of possible fuel leak-
age.
Prepare the necessary fire-extinguishing
appliance for immediate fire fighting in case
of fire.
NOTE:
Concerning the section where visible inspection
is difficult, the fuel odor provides a good indica-
tion of determining the fuel leakage.
Are there leaks from the fuel
delivery line?
Replace the faulty
fuel delivery line.
<Ref. to FU(w/o
STI)-194, Fuel
Delivery and Evap-
oration Lines.>
<Ref. to FU(w/o
STI)-51, Fuel
Injector.>
Go to step 2.
2 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 3.
3 CHECK EXPERIENCE OF RUNNING OUT OF
FUEL.
Check if there was an experience of running out
of fuel using “Check List for Interview”. <Ref. to
EN(w/o STI)(diag)-5, CHECK LIST NO. 2,
CHECK, Check List for Interview.>
Has the vehicle experienced
running out of fuel?
Finish the diagno-
sis.
NOTE:
DTC may be
stored by running
out of fuel.
Go to step 4.
15WRX_STI_US_EN.book 130 ージ 20  
EN(w/o STI)(diag)-131
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
4 CHECK FUEL PRESSURE.
1) Start the engine.
2) Using the Subaru Select Monitor, read the
values in «Fuel Rail Pressure A» and «Com-
manded Fuel Rail Pressure A» when racing the
engine.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value in «Fuel Rail Pres-
sure A» synchronized with the
one in «Commanded Fuel Rail
Pressure A»?
Go to step 5. The value in
«Fuel Rail Pres-
sure A» does not
increase: Go to
step 7.
The value in
«Fuel Rail Pres-
sure A» does not
change: Replace
the fuel pressure
sensor. <Ref. to
FU(w/o STI)-71,
Fuel Pressure
Sensor.>
5 CHECK OF FUEL PUMP.
1) Turn the ignition switch to ON. (engine OFF)
2) From «Fuel Pump Control» of «System
Operation Check Mode», check the operating
sound of the fuel pump when performing «ON/
OFF drive» for the fuel pump.
NOTE:
For detailed operation procedures, refer to “PC
application help for Subaru Select Monitor”.
Does the fuel pump emit oper-
ating sound?
Go to step 6. Check fuel pump
circuit. <Ref. to
EN(w/o STI)(diag)-
82, FUEL PUMP
CIRCUIT, Diag-
nostics for Engine
Starting Failure.>
6 CHECK FUEL PRESSURE (LOW PRESSURE
SIDE).
Check the fuel pressure on low-pressure side.
<Ref. to ME(w/o STI)-31, INSPECTION, Fuel
Pressure.>
Is the fuel pressure normal? Go to step 7. Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
7 CHECK FOR FUEL DELIVERY LINE LEAK-
AGE (HIGH PRESSURE SIDE).
1) Start the engine.
2) Using the Subaru Select Monitor, read the
change in value of «Fuel Rail Pressure A» when
stopping the engine.
NOTE:
In order to maintain the communication with
Subaru Select Monitor, turn the ignition switch
to OFF, and immediately turn it to ON.
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Does the value of «Fuel Rail
Pressure A» decrease rapidly?
Go to step 8. Go to step 9.
8 CHECK HIGH-PRESSURE FUEL PUMP.
Check the high-pressure fuel pump. <Ref. to
FU(w/o STI)-82, INSPECTION, High Pressure
Fuel Pump.>
Is the high-pressure fuel pump
normal?
Go to step 9. Replace the high-
pressure fuel
pump. <Ref. to
FU(w/o STI)-74,
High Pressure
Fuel Pump.>
Step Check Yes No
15WRX_STI_US_EN.book 131 ージ 20  
EN(w/o STI)(diag)-132
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
9 CHECK FOR REPRODUCTION OF FAILURE.
1) Perform the Clear Memory Mode. <Ref. to
EN(w/o STI)(diag)-61, Clear Memory Mode.>
2) Perform appropriate drive cycle test. <Ref.
to EN(w/o STI)(diag)-50, Drive Cycle.>
3) Read the DTC. <Ref. to EN(w/o STI)(diag)-
46, Read Diagnostic Trouble Code (DTC).>
Is the same DTC as current
diagnosis output?
Replace the high-
pressure fuel
pump. <Ref. to
FU(w/o STI)-74,
High Pressure
Fuel Pump.> After
replacement, go to
the next step. Go to
step 10.
NOTE:
When the high-
pressure fuel
pump has been re-
placed in step 8, go
to the next step
without replacing
the high-pressure
fuel pump. Go to
step 11.
End.
10 CHECK FOR REPRODUCTION OF FAILURE.
1) Perform the Clear Memory Mode. <Ref. to
EN(w/o STI)(diag)-61, Clear Memory Mode.>
2) Perform appropriate drive cycle test. <Ref.
to EN(w/o STI)(diag)-50, Drive Cycle.>
3) Read the DTC. <Ref. to EN(w/o STI)(diag)-
46, Read Diagnostic Trouble Code (DTC).>
Is the same DTC as current
diagnosis output?
Go to step 11.End.
11 CHECK FOR FUEL DELIVERY LINE LEAK-
AGE (HIGH PRESSURE SIDE).
1) Start the engine.
2) Using the Subaru Select Monitor, read the
change in value of «Fuel Rail Pressure A» when
stopping the engine.
NOTE:
In order to maintain the communication with
Subaru Select Monitor, turn the ignition switch
to OFF, and immediately turn it to ON.
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Does the value of «Fuel Rail
Pressure A» decrease rapidly?
Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
Repair the poor
contact of ECM
connector.
Step Check Yes No
15WRX_STI_US_EN.book 132 ージ 20  
EN(w/o STI)(diag)-133
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AA:DTC P0088 FUEL RAIL/SYSTEM PRESSURE - TOO HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-34, DTC P0088 FUEL RAIL/SYSTEM PRESSURE -
TOO HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Poor driving performance
Poor acceleration
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK FUEL PRESSURE.
1) Start the engine.
2) Using Subaru Select Monitor, read the val-
ues in «Fuel Rail Pressure A» and «Com-
manded Fuel Rail Pressure A» until the vehicle
is accelerated to 60 km/h (37.3 MPH) from the
parked state and stops again.
CAUTION:
Follow traffic rules and give the highest
priority to safe driving.
During driving, do not operate or gaze at
the Subaru Select Monitor.
Always check the measurement value af-
ter bringing the vehicle to a stop in a safe
place.
NOTE:
In order to apply the running load to the vehi-
cle, actually drive the vehicle, and read the
measurement value.
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value in «Fuel Rail Pres-
sure A» synchronized with the
one in «Commanded Fuel Rail
Pressure A»?
Replace the high-
pressure fuel
pump. <Ref. to
FU(w/o STI)-74,
High Pressure
Fuel Pump.> After
replacement, go to
the next step. Go to
step 3.
Replace the fuel
pressure sensor.
<Ref. to FU(w/o
STI)-71, Fuel Pres-
sure Sensor.>
3 CHECK FOR REPRODUCTION OF FAILURE.
1) Perform the Clear Memory Mode. <Ref. to
EN(w/o STI)(diag)-61, Clear Memory Mode.>
2) Perform appropriate drive cycle test. <Ref.
to EN(w/o STI)(diag)-50, Drive Cycle.>
3) Read the DTC. <Ref. to EN(w/o STI)(diag)-
46, Read Diagnostic Trouble Code (DTC).>
Is the same DTC as current
diagnosis output?
Repair the poor
contact of ECM
connector.
End.
15WRX_STI_US_EN.book 133 ージ 20  
EN(w/o STI)(diag)-134
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AB:DTC P0096 INTAKE AIR TEMPERATURE SENSOR #2 RANGE/PERFOR-
MANCE PROBLEM
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-35, DTC P0096 INTAKE AIR TEMPERATURE SENSOR
#2 RANGE/PERFORMANCE PROBLEM, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK CURRENT DATA.
1) Turn the ignition switch to ON.
2) Read the value of «IAT Sensor #12» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
3) Read the change of the value in «IAT Sen-
sor #12» while heating and cooling the manifold
absolute pressure and intake air temperature
sensor using a hair dryer.
CAUTION:
Do not heat the part to the temperature
where you cannot touch it with your bare
hand in order to prevent burning yourself
and protect the part.
Does the value of «IAT Sensor
#12» change between heating
and cooling?
Repair the poor
contact of ECM
connector.
Replace the mani-
fold absolute pres-
sure and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-120, Mani-
fold Absolute Pres-
sure and Intake Air
Temperature Sen-
sor.>
15WRX_STI_US_EN.book 134 ージ 20  
EN(w/o STI)(diag)-135
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AC:DTC P0097 INTAKE AIR TEMPERATURE SENSOR #2 CIRCUIT (LOW)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-37, DTC P0097 INTAKE AIR TEMPERATURE SENSOR
#2 CIRCUIT (LOW), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
E158B:
E159C:
E124
1
2
3
B25
C27
B4
EN-10320
1234
E124
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
4C19
ECM
(GRAY)
(BLACK)
MANIFOLD ABSOLUTE PRESSURE &
INTAKE AIR TEMPERATURE SENSOR
15WRX_STI_US_EN.book 135 ージ 20  
EN(w/o STI)(diag)-136
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «IAT Sensor #12» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value in «IAT Sensor
#12» 120°C (248°F) or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the manifold absolute pressure and intake air
temperature sensor.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 25 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the mani-
fold absolute pres-
sure and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-120, Mani-
fold Absolute Pres-
sure and Intake Air
Temperature Sen-
sor.>
Repair the ground
short circuit of har-
ness between
ECM connector
and the manifold
absolute pressure
and intake air tem-
perature sensor
connector.
15WRX_STI_US_EN.book 136 ージ 20  
EN(w/o STI)(diag)-137
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AD:DTC P0098 INTAKE AIR TEMPERATURE SENSOR #2 CIRCUIT (HIGH)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-38, DTC P0098 INTAKE AIR TEMPERATURE SENSOR
#2 CIRCUIT (HIGH), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
E158B:
E159C:
E124
1
2
3
B25
C27
B4
EN-10320
1234
E124
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
4C19
ECM
(GRAY)
(BLACK)
MANIFOLD ABSOLUTE PRESSURE &
INTAKE AIR TEMPERATURE SENSOR
15WRX_STI_US_EN.book 137 ージ 20  
EN(w/o STI)(diag)-138
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «IAT Sensor #12» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value in «IAT Sensor
#12» less than –40°C (–40°F)?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and manifold
absolute pressure and intake air temperature
sensor connector.
Is there poor contact of ECM or
manifold absolute pressure and
intake air temperature sensor
connector?
Repair the poor
contact of ECM or
manifold absolute
pressure and
intake air tempera-
ture sensor con-
nector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the manifold absolute pressure and intake air
temperature sensor.
3) Measure the resistance of harness between
ECM connector and the manifold absolute pres-
sure and intake air temperature sensor connec-
tor.
Connector & terminal
(E158) No. 25 — (E124) No. 1:
(E159) No. 27 — (E124) No. 2:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit of the har-
ness between the
ECM connector
and the manifold
absolute pressure
& intake air tem-
perature sensor
connector.
4 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E158) No. 25 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
harness between
ECM connector
and the manifold
absolute pressure
and intake air tem-
perature sensor
connector.
Replace the mani-
fold absolute pres-
sure and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-120, Mani-
fold Absolute Pres-
sure and Intake Air
Temperature Sen-
sor.>
15WRX_STI_US_EN.book 138 ージ 20  
EN(w/o STI)(diag)-139
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AE:DTC P0101 MASS OR VOLUME AIR FLOW CIRCUIT RANGE/PERFOR-
MANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-39, DTC P0101 MASS OR VOLUME AIR FLOW CIR-
CUIT RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
15WRX_STI_US_EN.book 139 ージ 20  
EN(w/o STI)(diag)-140
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AF:DTC P0102 MASS OR VOLUME AIR FLOW CIRCUIT LOW INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-41, DTC P0102 MASS OR VOLUME AIR FLOW CIR-
CUIT LOW INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
9
E3 B22
78
5
6
34
2
1
B122
EN-10799
B3
123
4
5
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
*
*
B122
J/C
B3
1
B550
215
01
B220
11
2
3
4
B134A:
E158B:
A19
B5
A16
A28
5
*
SBF-7
ECM
*
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
: TERMINAL No. OPTIONAL
ARRANGEMENT
MAIN RELAY
BATTERY
FUSE HOLDER
MASS AIR FLOW &
INTAKE AIR TEMPERATURE SENSOR
(BROWN)
(BLACK)
15WRX_STI_US_EN.book 140 ージ 20  
EN(w/o STI)(diag)-141
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Air Flow Sensor Volt-
age» using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «Air Flow Sensor
Voltage» less than 0.2 V?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK POWER SUPPLY OF MASS AIR
FLOW AND INTAKE AIR TEMPERATURE
SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the mass
air flow and intake air temperature sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between mass air flow
and intake air temperature sensor connector
and engine ground.
Connector & terminal
(B3) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
main relay and
mass air flow and
intake air tempera-
ture sensor con-
nector
Poor contact of
main relay connec-
tor
3 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and the mass air flow and
intake air temperature sensor connector.
Connector & terminal
(B134) No. 16 — (B3) No. 3:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit of harness
between ECM con-
nector and the
mass air flow and
intake air tempera-
ture sensor con-
nector.
4 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(B134) No. 16 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the ground
short circuit of har-
ness between
ECM connector
and the mass air
flow and intake air
temperature sen-
sor connector.
5 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and mass air
flow and intake air temperature sensor connec-
tor.
Is there poor contact of ECM or
mass air flow and intake air
temperature sensor connector?
Repair the poor
contact of ECM or
mass air flow and
intake air tempera-
ture sensor con-
nector.
Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
15WRX_STI_US_EN.book 141 ージ 20  
EN(w/o STI)(diag)-142
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AG:DTC P0103 MASS OR VOLUME AIR FLOW CIRCUIT HIGH INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-42, DTC P0103 MASS OR VOLUME AIR FLOW CIR-
CUIT HIGH INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
9
E3 B22
78
5
6
34
2
1
B122
EN-10799
B3
123
4
5
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
*
*
B122
J/C
B3
1
B550
215
01
B220
11
2
3
4
B134A:
E158B:
A19
B5
A16
A28
5
*
SBF-7
ECM
*
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
: TERMINAL No. OPTIONAL
ARRANGEMENT
MAIN RELAY
BATTERY
FUSE HOLDER
MASS AIR FLOW &
INTAKE AIR TEMPERATURE SENSOR
(BROWN)
(BLACK)
15WRX_STI_US_EN.book 142 ージ 20  
EN(w/o STI)(diag)-143
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Air Flow Sensor Volt-
age» using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «Air Flow Sensor
Voltage» 5 V or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the mass
air flow and intake air temperature sensor.
3) Start the engine.
4) Read the value of «Air Flow Sensor Volt-
age» using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «Air Flow Sensor
Voltage» 5 V or more?
Repair the short
circuit of harness
to power supply
between ECM con-
nector and the
mass air flow and
intake air tempera-
ture sensor con-
nector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between
mass air flow and intake air temperature sensor
connector and engine ground.
Connector & terminal
(B3) No. 2 — Engine ground:
Is the resistance less than 5 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and the mass air
flow and intake air
temperature sen-
sor connector
Poor contact of
ECM connector
4 CHECK FOR POOR CONTACT.
Check for poor contact of mass air flow and
intake air temperature sensor connector.
Is there poor contact of mass
air flow and intake air tempera-
ture sensor connector?
Repair the poor
contact of mass air
flow and intake air
temperature sen-
sor connector.
Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
15WRX_STI_US_EN.book 143 ージ 20  
EN(w/o STI)(diag)-144
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AH:DTC P0107 MANIFOLD ABSOLUTE PRESSURE/BAROMETRIC PRESSURE
CIRCUIT LOW INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-43, DTC P0107 MANIFOLD ABSOLUTE PRESSURE/
BAROMETRIC PRESSURE CIRCUIT LOW INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
E158B:
E159C:
E124
1
2
3
B25
C27
B4
EN-10320
1234
E124
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
4C19
ECM
(GRAY)
(BLACK)
MANIFOLD ABSOLUTE PRESSURE &
INTAKE AIR TEMPERATURE SENSOR
15WRX_STI_US_EN.book 144 ージ 20  
EN(w/o STI)(diag)-145
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Mani. Absolute Pres-
sure» using the Subaru Select Monitor or a gen-
eral scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Mani. Absolute
Pressure» less than 13.3 kPa
(100 mmHg, 3.94 inHg)?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK POWER SUPPLY OF MANIFOLD
ABSOLUTE PRESSURE AND INTAKE AIR
TEMPERATURE SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the manifold
absolute pressure and intake air temperature
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between the manifold
absolute pressure and intake air temperature
sensor connector and engine ground.
Connector & terminal
(E124) No. 4 (+) — Engine ground (–):
Is the voltage 4.5 V or more? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and the manifold
absolute pressure
and intake air tem-
perature sensor
connector
Poor contact of
ECM connector
3 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and the manifold absolute pres-
sure and intake air temperature sensor connec-
tor.
Connector & terminal
(E158) No. 4 — (E124) No. 3:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit in harness
between the mani-
fold absolute pres-
sure and intake air
temperature sen-
sor connector.
4 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 4 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the ground
short circuit of har-
ness between
ECM connector
and the manifold
absolute pressure
and intake air tem-
perature sensor
connector.
15WRX_STI_US_EN.book 145 ージ 20  
EN(w/o STI)(diag)-146
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
5 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and manifold
absolute pressure and intake air temperature
sensor connector.
Is there poor contact of ECM or
manifold absolute pressure and
intake air temperature sensor
connector?
Repair the poor
contact of ECM or
manifold absolute
pressure and
intake air tempera-
ture sensor con-
nector.
Replace the mani-
fold absolute pres-
sure and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-120, Mani-
fold Absolute Pres-
sure and Intake Air
Temperature Sen-
sor.>
Step Check Yes No
15WRX_STI_US_EN.book 146 ージ 20  
EN(w/o STI)(diag)-147
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AI: DTC P0108 MANIFOLD ABSOLUTE PRESSURE/BAROMETRIC PRESSURE
CIRCUIT HIGH INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-44, DTC P0108 MANIFOLD ABSOLUTE PRESSURE/
BAROMETRIC PRESSURE CIRCUIT HIGH INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
E158B:
E159C:
E124
1
2
3
B25
C27
B4
EN-10320
1234
E124
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
4C19
ECM
(GRAY)
(BLACK)
MANIFOLD ABSOLUTE PRESSURE &
INTAKE AIR TEMPERATURE SENSOR
15WRX_STI_US_EN.book 147 ージ 20  
EN(w/o STI)(diag)-148
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Mani. Absolute Pres-
sure» using the Subaru Select Monitor or a gen-
eral scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Mani. Absolute
Pressure» 256 kPa (1,920.2
mmHg, 75.6 inHg) or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the manifold
absolute pressure and intake air temperature
sensor.
3) Start the engine.
4) Read the value of «Mani. Absolute Pres-
sure» using the Subaru Select Monitor or a gen-
eral scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Mani. Absolute
Pressure» 256 kPa (1,920.2
mmHg, 75.6 inHg) or more?
Repair the short
circuit to power in
harness between
ECM connector
and the manifold
absolute pressure
and intake air tem-
perature sensor
connector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between
manifold absolute pressure and intake air tem-
perature sensor connector and engine ground.
Connector & terminal
(E124) No. 2 — Engine ground:
Is the resistance less than 5 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and the manifold
absolute pressure
and intake air tem-
perature sensor
connector
Poor contact of
ECM connector
15WRX_STI_US_EN.book 148 ージ 20  
EN(w/o STI)(diag)-149
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
4 CHECK FOR POOR CONTACT.
Check for poor contact of the manifold absolute
pressure and intake air temperature sensor
connector.
Is there poor contact of the
manifold absolute pressure and
intake air temperature sensor
connector?
Repair the poor
contact of the man-
ifold absolute pres-
sure and intake air
temperature sen-
sor connector.
Replace the mani-
fold absolute pres-
sure and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-120, Mani-
fold Absolute Pres-
sure and Intake Air
Temperature Sen-
sor.>
Step Check Yes No
15WRX_STI_US_EN.book 149 ージ 20  
EN(w/o STI)(diag)-150
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AJ:DTC P0111 INTAKE AIR TEMPERATURE SENSOR RANGE/PERFORMANCE
PROBLEM
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-45, DTC P0111 INTAKE AIR TEMPERATURE SENSOR
RANGE/PERFORMANCE PROBLEM, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK CURRENT DATA.
1) Turn the ignition switch to ON.
2) Read the value of «IAT Sensor #11» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
3) Read the change of the value in «IAT Sen-
sor #11» while heating and cooling the mass air
flow and intake air temperature sensor using a
hair dryer.
CAUTION:
Do not heat the part to the temperature
where you cannot touch it with your bare
hand in order to prevent burning yourself
and protect the part.
Does the value of «IAT Sensor
#11» change between heating
and cooling?
Repair the poor
contact of ECM
connector.
Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
15WRX_STI_US_EN.book 150 ージ 20  
EN(w/o STI)(diag)-151
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AK:DTC P0112 INTAKE AIR TEMPERATURE SENSOR 1 CIRCUIT LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-48, DTC P0112 INTAKE AIR TEMPERATURE SENSOR
1 CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
9
E3 B22
78
5
6
34
2
1
B122
EN-10799
B3
123
4
5
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
*
*
B122
J/C
B3
1
B550
215
01
B220
11
2
3
4
B134A:
E158B:
A19
B5
A16
A28
5
*
SBF-7
ECM
*
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
: TERMINAL No. OPTIONAL
ARRANGEMENT
MAIN RELAY
BATTERY
FUSE HOLDER
MASS AIR FLOW &
INTAKE AIR TEMPERATURE SENSOR
(BROWN)
(BLACK)
15WRX_STI_US_EN.book 151 ージ 20  
EN(w/o STI)(diag)-152
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «IAT Sensor #11» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value in «IAT Sensor
#11» 120°C (248°F) or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the mass air flow and intake air temperature
sensor.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 5 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
Repair the ground
short circuit of har-
ness between
ECM connector
and the mass air
flow and intake air
temperature sen-
sor connector.
15WRX_STI_US_EN.book 152 ージ 20  
EN(w/o STI)(diag)-153
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AL:DTC P0113 INTAKE AIR TEMPERATURE SENSOR 1 CIRCUIT HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-49, DTC P0113 INTAKE AIR TEMPERATURE SENSOR
1 CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
9
E3 B22
78
5
6
34
2
1
B122
EN-10799
B3
123
4
5
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
*
*
B122
J/C
B3
1
B550
215
01
B220
11
2
3
4
B134A:
E158B:
A19
B5
A16
A28
5
*
SBF-7
ECM
*
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
: TERMINAL No. OPTIONAL
ARRANGEMENT
MAIN RELAY
BATTERY
FUSE HOLDER
MASS AIR FLOW &
INTAKE AIR TEMPERATURE SENSOR
(BROWN)
(BLACK)
15WRX_STI_US_EN.book 153 ージ 20  
EN(w/o STI)(diag)-154
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «IAT Sensor #11» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value in «IAT Sensor
#11» less than –40°C (–40°F)?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and mass air
flow and intake air temperature sensor connec-
tor.
Is there poor contact of ECM or
mass air flow and intake air
temperature sensor connector?
Repair the poor
contact of ECM or
mass air flow and
intake air tempera-
ture sensor con-
nector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the mass air flow and intake air temperature
sensor.
3) Measure the resistance of harness between
ECM connector and the mass air flow and
intake air temperature sensor connector.
Connector & terminal
(E158) No. 5 — (B3) No. 4:
(B134) No. 19 — (B3) No. 5:
Is the resistance less than 1 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and the mass air
flow and intake air
temperature sen-
sor connector
Poor contact of
coupling connector
4 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E158) No. 5 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit of harness
to power supply
between ECM con-
nector and the
mass air flow and
intake air tempera-
ture sensor con-
nector.
Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
15WRX_STI_US_EN.book 154 ージ 20  
EN(w/o STI)(diag)-155
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AM:DTC P0116 ENGINE COOLANT TEMPERATURE SENSOR 1 CIRCUIT
RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-50, DTC P0116 ENGINE COOLANT TEMPERATURE
SENSOR 1 CIRCUIT RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Hard to start
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Disconnect the connectors from the engine
coolant temperature sensor.
2) Measure the resistance between engine
coolant temperature sensor terminals when the
engine coolant is cold and after warmed up.
Terminals
No. 1 — No. 2:
Is the resistance of engine cool-
ant temperature sensor differ-
ent between when engine
coolant is cold and after
warmed up?
Repair the poor
contact of ECM
connector.
Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
15WRX_STI_US_EN.book 155 ージ 20  
EN(w/o STI)(diag)-156
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AN:DTC P0117 ENGINE COOLANT TEMPERATURE CIRCUIT LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-52, DTC P0117 ENGINE COOLANT TEMPERATURE
CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Hard to start
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
E158B:
E159C:
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
12
E8
E8
1
2
C27
B38
EN-10322
ECM
ENGINE COOLANT
TEMPERATURE
SENSOR
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 156 ージ 20  
EN(w/o STI)(diag)-157
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Coolant Temp.» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Coolant Temp
150°C (302°F) or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
engine coolant temperature sensor.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 38 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
Repair the short
circuit to ground in
harness between
ECM connector
and engine coolant
temperature sen-
sor connector.
15WRX_STI_US_EN.book 157 ージ 20  
EN(w/o STI)(diag)-158
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AO:DTC P0118 ENGINE COOLANT TEMPERATURE CIRCUIT HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-53, DTC P0118 ENGINE COOLANT TEMPERATURE
CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Hard to start
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
E158B:
E159C:
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
12
E8
E8
1
2
C27
B38
EN-10322
ECM
ENGINE COOLANT
TEMPERATURE
SENSOR
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 158 ージ 20  
EN(w/o STI)(diag)-159
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Coolant Temp.» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Coolant Temp
less than –40°C (–40°F)?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and engine cool-
ant temperature sensor connector.
Is there poor contact of ECM or
engine coolant temperature
sensor connector?
Repair the poor
contact of ECM or
engine coolant
temperature sen-
sor connector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
engine coolant temperature sensor.
3) Measure the resistance of harness between
ECM connector and engine coolant tempera-
ture sensor connector.
Connector & terminal
(E159) No. 27 — (E8) No. 1:
(E158) No. 38 — (E8) No. 2:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit of the har-
ness between the
ECM connector
and engine coolant
temperature sen-
sor connector.
4 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E158) No. 38 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit of harness
to power supply
between ECM con-
nector and engine
coolant tempera-
ture sensor con-
nector.
Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
15WRX_STI_US_EN.book 159 ージ 20  
EN(w/o STI)(diag)-160
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AP:DTC P0122 THROTTLE/PEDAL POSITION SENSOR/SWITCH “A” CIRCUIT
LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-54, DTC P0122 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “A” CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 160 ージ 20  
EN(w/o STI)(diag)-161
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 18 — Engine ground:
(E158) No. 17 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 2. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
ECM
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B225
14
17
15
16
B550
215
317
B220
1011
E57
B17
B29
B18
B30
6
5
3
2
4
1
C1
C2
A39
A11
B225B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10800
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
BATTERY
ELECTRONIC
THROTTLE
CONTROL
MAIN RELAY
FUSE HOLDER
ELECTRONIC
THROTTLE CONTROL
RELAY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 161 ージ 20  
EN(w/o STI)(diag)-162
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 1 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the elec-
tronic throttle con-
trol. <Ref. to FU(w/
o STI)-15, Throttle
Body.>
Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
Replace the ECM if
defective. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
Step Check Yes No
15WRX_STI_US_EN.book 162 ージ 20  
EN(w/o STI)(diag)-163
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AQ:DTC P0123 THROTTLE/PEDAL POSITION SENSOR/SWITCH “A” CIRCUIT
HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-55, DTC P0123 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “A” CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 163 ージ 20  
EN(w/o STI)(diag)-164
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance of harness between
ECM connector and electronic throttle control
connector.
Connector & terminal
(E158) No. 17 — (E57) No. 1:
(E158) No. 30 — (E57) No. 3:
Is the resistance less than 1 Ω? Go to step 2. Repair the open
circuit of harness
between ECM con-
nector and elec-
tronic throttle
control connector.
ECM
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B225
14
17
15
16
B550
215
317
B220
1011
E57
B17
B29
B18
B30
6
5
3
2
4
1
C1
C2
A39
A11
B225B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10800
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
BATTERY
ELECTRONIC
THROTTLE
CONTROL
MAIN RELAY
FUSE HOLDER
ELECTRONIC
THROTTLE CONTROL
RELAY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 164 ージ 20  
EN(w/o STI)(diag)-165
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 3 — Engine ground:
Is the resistance less than 5 Ω? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
ECM connector
Poor contact of
coupling connector
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 1 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(E158) No. 17 — (E158) No. 18:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to FU(w/o
STI)-15, Throttle
Body.>
Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Step Check Yes No
15WRX_STI_US_EN.book 165 ージ 20  
EN(w/o STI)(diag)-166
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AR:DTC P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP
FUEL CONTROL
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-56, DTC P0125 INSUFFICIENT COOLANT TEMPERA-
TURE FOR CLOSED LOOP FUEL CONTROL, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine does not return to idle.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK TIRE SIZE. Is the tire size as specified and
the same size as three other
wheels?
Go to step 2. Replace the tire.
2 CHECK ENGINE COOLANT.
Check the following items:
Amount of engine coolant
Engine coolant freeze
Contamination of engine coolant
Is the engine coolant normal? Go to step 3. Fill or replace the
engine coolant.
<Ref. to CO(w/o
STI)-13,
REPLACEMENT,
Engine Coolant.>
3 CHECK THERMOSTAT. Does the thermostat remain
opened?
Replace the ther-
mostat. <Ref. to
CO(w/o STI)-33,
Thermostat.>
Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
15WRX_STI_US_EN.book 166 ージ 20  
EN(w/o STI)(diag)-167
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AS:DTC P0128 COOLANT THERMOSTAT (ENGINE COOLANT TEMPERATURE
BELOW THERMOSTAT REGULATING TEMPERATURE)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-58, DTC P0128 COOLANT THERMOSTAT (ENGINE
COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE), Diagnostic Trouble
Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Thermostat remains open.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK ENGINE COOLANT. Is the engine coolant amount
normal?
Go to step 3. Refill the engine
coolant. <Ref. to
CO(w/o STI)-13,
Engine Coolant.>
3 CHECK RADIATOR FAN.
1) Start the engine.
2) Check the radiator fan operation.
Does the radiator fan continu-
ously rotate for 3 minutes or
more during idling?
Repair radiator fan
circuit. <Ref. to
CO(w/o STI)-46,
Radiator Main Fan
and Fan Motor.>
<Ref. to CO(w/o
STI)-49, Radiator
Sub Fan and Fan
Motor.>
Replace the ther-
mostat. <Ref. to
CO(w/o STI)-33,
Thermostat.>
15WRX_STI_US_EN.book 167 ージ 20  
EN(w/o STI)(diag)-168
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AT:DTC P0130 O2 SENSOR CIRCUIT (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-61, DTC P0130 O2 SENSOR CIRCUIT (BANK 1 SEN-
SOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 168 ージ 20  
EN(w/o STI)(diag)-169
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FRONT OXYGEN (A/F) SENSOR DA-
TA.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) Idle the engine for one minute or more.
3) Read the value of «A/F Sensor #11» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «A/F Sensor
#11» 1.20 — 3.00 V?
Go to step 2. Go to step 3.
2 CHECK FRONT OXYGEN (A/F) SENSOR DA-
TA.
1) Race the engine so that the engine speed
reaches 3,000 rpm. (Five times in total)
2) Read the value of «A/F Sensor #11» at rac-
ing using the Subaru Select Monitor or a gen-
eral scan tool.
NOTE:
To increase engine speed to 3,000 rpm, slow-
ly depress accelerator pedal for approximately
5 seconds, and quickly release accelerator ped-
al to decrease engine speed.
Normally, the air fuel ratio is rich during rac-
ing.
Is the value of «A/F Sensor
#11» 2.5 V or more?
Go to step 5. Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
front oxygen (A/F) sensor.
3) Measure the resistance of harness between
ECM connector and front oxygen (A/F) sensor
connector.
Connector & terminal
(E158) No. 15 — (E24) No. 1:
(E158) No. 27 — (E24) No. 4:
(E158) No. 39 — (E24) No. 5:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit of harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
4 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 15 — Engine ground:
(E158) No. 27 — Engine ground:
(E158) No. 39 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector.
15WRX_STI_US_EN.book 169 ージ 20  
EN(w/o STI)(diag)-170
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
5 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items.
Looseness and improper fitting of exhaust
system parts
Damage (crack, hole etc.) of parts
Looseness of front oxygen (A/F) sensor
Loose part and improper installation between
front oxygen (A/F) sensor and rear oxygen sen-
sor
Is there any fault in exhaust
system?
Repair or replace
faulty parts.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
Step Check Yes No
15WRX_STI_US_EN.book 170 ージ 20  
EN(w/o STI)(diag)-171
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AU:DTC P0131 O2 SENSOR CIRCUIT LOW VOLTAGE (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-62, DTC P0131 O2 SENSOR CIRCUIT LOW VOLTAGE
(BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 171 ージ 20  
EN(w/o STI)(diag)-172
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FRONT OXYGEN (A/F) SENSOR
CONNECTOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
front oxygen (A/F) sensor.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 15 — Engine ground:
(E158) No. 27 — Engine ground:
(E158) No. 39 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 3. Repair the short
circuit to ground in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector.
3 CHECK FOR POOR CONTACT.
Check for poor contact of the front oxygen (A/F)
sensor connector.
Is there poor contact of front
oxygen (A/F) sensor connec-
tor?
Repair the poor
contact of front
oxygen (A/F) sen-
sor connector.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
15WRX_STI_US_EN.book 172 ージ 20  
EN(w/o STI)(diag)-173
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AV:DTC P0132 O2 SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-63, DTC P0132 O2 SENSOR CIRCUIT HIGH VOLTAGE
(BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 173 ージ 20  
EN(w/o STI)(diag)-174
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FRONT OXYGEN (A/F) SENSOR
CONNECTOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from front oxy-
gen (A/F) sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E158) No. 15 (+) — Engine ground (–):
(E158) No. 27 (+) — Engine ground (–):
(E158) No. 39 (+) — Engine ground (–):
Is the voltage 8 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
15WRX_STI_US_EN.book 174 ージ 20  
EN(w/o STI)(diag)-175
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AW:DTC P0134 O2 SENSOR CIRCUIT NO ACTIVITY DETECTED (BANK 1 SEN-
SOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-64, DTC P0134 O2 SENSOR CIRCUIT NO ACTIVITY
DETECTED (BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 175 ージ 20  
EN(w/o STI)(diag)-176
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
front oxygen (A/F) sensor.
3) Measure the resistance of harness between
ECM connector and front oxygen (A/F) sensor
connector.
Connector & terminal
(E158) No. 15 — (E24) No. 1:
(E158) No. 27 — (E24) No. 4:
(E158) No. 39 — (E24) No. 5:
Is the resistance less than 1 Ω? Go to step 2. Repair the open
circuit of harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and front oxygen
(A/F) sensor connector.
Is there poor contact of ECM or
front oxygen (A/F) sensor con-
nector?
Repair the poor
contact of ECM or
front oxygen (A/F)
sensor connector.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
15WRX_STI_US_EN.book 176 ージ 20  
EN(w/o STI)(diag)-177
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AX:DTC P0137 O2 SENSOR CIRCUIT LOW VOLTAGE (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-66, DTC P0137 O2 SENSOR CIRCUIT LOW VOLTAGE
(BANK 1 SENSOR 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 177 ージ 20  
EN(w/o STI)(diag)-178
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
keep the engine speed at 3,000 rpm. (2 minutes
maximum)
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» 0.490 V or more?
Go to step 6. Go to step 2.
2 CHECK REAR OXYGEN SENSOR CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 42 — (E25) No. 3:
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit of harness
between ECM con-
nector and rear
oxygen sensor
connector.
4 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 16 — Engine ground
(E158) No. 42 — Engine ground
Is the resistance 1 Ω or more? Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and rear oxygen
sensor connector.
5 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between rear oxygen
sensor connector and engine ground.
Connector & terminal
(E25) No. 3 (+) — Engine ground (–):
Is the voltage 1.8 V or more? Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
6 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items.
Looseness and improper fitting of exhaust
system parts
Damage (crack, hole etc.) of parts
Loose part and improper installation between
front oxygen (A/F) sensor and rear oxygen sen-
sor
Is there any fault in exhaust
system?
Repair or replace
faulty parts.
Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
15WRX_STI_US_EN.book 178 ージ 20  
EN(w/o STI)(diag)-179
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AY:DTC P0138 O2 SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-67, DTC P0138 O2 SENSOR CIRCUIT HIGH VOLTAGE
(BANK 1 SENSOR 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 179 ージ 20  
EN(w/o STI)(diag)-180
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
rapidly reduce the engine speed from 3,000
rpm.
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» 0.250 V or less?
Go to step 5. Go to step 2.
2 CHECK REAR OXYGEN SENSOR CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 42 — (E25) No. 3:
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit of harness
between ECM con-
nector and rear
oxygen sensor
connector.
4 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between rear oxygen
sensor connector and engine ground.
Connector & terminal
(E25) No. 3 (+) — Engine ground (–):
Is the voltage 2.3 V or less? Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
5 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items.
Looseness and improper fitting of exhaust
system parts
Damage (crack, hole etc.) of parts
Loose part and improper installation between
front oxygen (A/F) sensor and rear oxygen sen-
sor
Is there any fault in exhaust
system?
Repair or replace
faulty parts.
Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
15WRX_STI_US_EN.book 180 ージ 20  
EN(w/o STI)(diag)-181
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
AZ:DTC P013A O2 SENSOR SLOW RESPONSE - RICH TO LEAN (BANK 1 SEN-
SOR 2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-68, DTC P013A O2 SENSOR SLOW RESPONSE -
RICH TO LEAN (BANK 1 SENSOR 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 181 ージ 20  
EN(w/o STI)(diag)-182
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BA:DTC P013B O2 SENSOR SLOW RESPONSE - LEAN TO RICH (BANK 1 SEN-
SOR 2)
NOTE:
For the diagnostic procedure, refer to DTC P013A. <Ref. to EN(w/o STI)(diag)-181, DTC P013A O2 SEN-
SOR SLOW RESPONSE - RICH TO LEAN (BANK 1 SENSOR 2), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
BB:DTC P013E O2 SENSOR DELAYED RESPONSE - RICH TO LEAN (BANK 1
SENSOR 2)
NOTE:
For the diagnostic procedure, refer to DTC P013A. <Ref. to EN(w/o STI)(diag)-181, DTC P013A O2 SEN-
SOR SLOW RESPONSE - RICH TO LEAN (BANK 1 SENSOR 2), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
BC:DTC P013F O2 SENSOR DELAYED RESPONSE - LEAN TO RICH (BANK 1
SENSOR 2)
NOTE:
For the diagnostic procedure, refer to DTC P013A. <Ref. to EN(w/o STI)(diag)-181, DTC P013A O2 SEN-
SOR SLOW RESPONSE - RICH TO LEAN (BANK 1 SENSOR 2), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 2. Repair the open
circuit of harness
between ECM con-
nector and rear
oxygen sensor
connector.
2 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
Measure the resistance between rear oxygen
sensor connector and engine ground.
Connector & terminal
(E25) No. 4 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 3. Repair the short
circuit to ground in
harness between
ECM connector
and rear oxygen
sensor connector.
3 CHECK REAR OXYGEN SENSOR.
Measure the resistance between rear oxygen
sensor terminals.
Terminals
No. 3 — No. 4
Is the resistance less than 1 Ω? Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
15WRX_STI_US_EN.book 182 ージ 20  
EN(w/o STI)(diag)-183
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BD:DTC P0141 O2 SENSOR HEATER CIRCUIT (BANK1 SENSOR2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-76, DTC P0141 O2 SENSOR HEATER CIRCUIT
(BANK1 SENSOR2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 183 ージ 20  
EN(w/o STI)(diag)-184
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK POWER SUPPLY TO REAR OXY-
GEN SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear oxygen
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between rear oxygen
sensor connector and engine ground.
Connector & terminal
(E25) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the power
supply line.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
A/F, oxygen sen-
sor relay and rear
oxygen sensor
connector
Poor contact of
A/F, oxygen sen-
sor relay connector
Poor contact of
coupling connector
Malfunction of A/
F, oxygen sensor
relay
2 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and rear oxygen sensor connector.
Connector & terminal
(E25) No. 2 — (E159) No. 3:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit of harness
between ECM con-
nector and rear
oxygen sensor
connector.
3 CHECK GROUND CIRCUIT FOR ECM.
Measure the resistance of harness between
ECM connector and engine ground.
Connector & terminal
(B134) No. 35 — Engine ground:
(B134) No. 47 — Engine ground:
(E159) No. 10 — Engine ground:
(E159) No. 17 — Engine ground:
(E159) No. 18 — Engine ground:
(E159) No. 25 — Engine ground:
(E159) No. 26 — Engine ground:
Is the resistance less than 5 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
coupling connector
4 CHECK REAR OXYGEN SENSOR.
Measure the resistance between rear oxygen
sensor connector terminals.
Terminals
No. 1 — No. 2:
Is the resistance 5.4 — 7.3 Ω? Repair the poor
contact of ECM
connector.
Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
15WRX_STI_US_EN.book 184 ージ 20  
EN(w/o STI)(diag)-185
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BE:DTC P014C O2 SENSOR SLOW RESPONSE - RICH TO LEAN (BANK 1 SEN-
SOR 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-77, DTC P014C O2 SENSOR SLOW RESPONSE -
RICH TO LEAN (BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
BF:DTC P014D O2 SENSOR SLOW RESPONSE - LEAN TO RICH (BANK 1 SEN-
SOR 1)
NOTE:
For the diagnostic procedure, refer to DTC P014C. <Ref. to EN(w/o STI)(diag)-185, DTC P014C O2 SEN-
SOR SLOW RESPONSE - RICH TO LEAN (BANK 1 SENSOR 1), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
BG:DTC P015A O2 SENSOR DELAYED RESPONSE - RICH TO LEAN (BANK 1
SENSOR 1)
NOTE:
For the diagnostic procedure, refer to DTC P014C. <Ref. to EN(w/o STI)(diag)-185, DTC P014C O2 SEN-
SOR SLOW RESPONSE - RICH TO LEAN (BANK 1 SENSOR 1), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
BH:DTC P015B O2 SENSOR DELAYED RESPONSE - LEAN TO RICH (BANK 1
SENSOR 1)
NOTE:
For the diagnostic procedure, refer to DTC P014C. <Ref. to EN(w/o STI)(diag)-185, DTC P014C O2 SEN-
SOR SLOW RESPONSE - RICH TO LEAN (BANK 1 SENSOR 1), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
BI: DTC P0171 SYSTEM TOO LEAN (BANK 1)
NOTE:
For the diagnostic procedure, refer to DTC P0172. <Ref. to EN(w/o STI)(diag)-186, DTC P0172 SYSTEM
TOO RICH (BANK 1), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
Step Check Yes No
1 CHECK EXHAUST SYSTEM.
NOTE:
Check the following items.
Loose installation of front portion of exhaust
pipe onto cylinder heads
Loose connection between front exhaust pipe
and front catalytic converter
Damage of exhaust pipe resulting in a hole
Is there any fault in exhaust
system?
Repair the exhaust
system.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
15WRX_STI_US_EN.book 185 ージ 20  
EN(w/o STI)(diag)-186
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BJ:DTC P0172 SYSTEM TOO RICH (BANK 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-86, DTC P0172 SYSTEM TOO RICH (BANK 1), Diag-
nostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
2
E6
E5
E17
E16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
2
1
E5
B11
B23
B35
EN-10794
2
1
E16
2
1
E6
2
1
E17
B47
B12
B24
B36
B48
C18
C17
C10
A35
A47
16
15
E3
B22
C26
C25
B134A:
E158B:
C: E159
ECM
FUEL INJECTOR No. 4
FUEL INJECTOR No. 3
FUEL INJECTOR No. 2
FUEL INJECTOR No. 1
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 186 ージ 20  
EN(w/o STI)(diag)-187
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
#1 (E158) No. 11 — (E158) No. 12:
#2 (E158) No. 23 — (E158) No. 24:
#3 (E158) No. 35 — (E158) No. 36:
#4 (E158) No. 47 — (E158) No. 48:
Is resistance 1.89 — 2.31 Ω at
20°C (68°F)?
Go to step 3. Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Disconnect the connector from fuel injector.
2) Measure the resistance of harness between
ECM connector and defective fuel injector con-
nector.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Repair or replace
the following items.
Poor contact of
fuel injector con-
nector
Defective fuel
injector <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
3 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Disconnect the connector from fuel injector.
2) Measure the resistance between ECM con-
nector and engine ground on defective fuel
injectors.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the faulty
fuel injector. <Ref.
to FU(w/o STI)-51,
Fuel Injector.>
Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
5 CHECK EXHAUST SYSTEM. Are there holes or loose bolts
on exhaust system?
Repair the exhaust
system.
Go to step 6.
6 CHECK AIR INTAKE SYSTEM. Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
Go to step 7.
15WRX_STI_US_EN.book 187 ージ 20  
EN(w/o STI)(diag)-188
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
7 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 328 —
358 kPa (3.3 — 3.7 kgf/cm
2
, 48
— 52 psi)?
Go to step 8. Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
8 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm up completely.
2) Read the value of «Coolant Temp.» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Coolant Temp
75°C (167°F) or more?
Go to step 9. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
9 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Read the value of «Mass Air Flow» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Mass Air
Flow» 2.0 — 5.0 g/s (0.26 —
0.66 lb/m)?
Go to step 10. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 188 ージ 20  
EN(w/o STI)(diag)-189
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
10 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Open the front hood.
6) Measure the ambient temperature.
7) Read the value of «IAT Sensor #11» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Subtract ambient temperature
value from the value of «IAT
Sensor #11». Is the obtained
value –10 — 50°C (–18 —
90°F)?
Go to step 11. Check the mass air
flow and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-118, Mass
Air Flow and Intake
Air Temperature
Sensor.>
11 CHECK FUEL INJECTOR.
Check fuel injector. <Ref. to FU(w/o STI)-70,
INSPECTION, Fuel Injector.>
Are fuel injectors OK? Repair the poor
contact of ECM
connector.
Replace the faulty
fuel injector. <Ref.
to FU(w/o STI)-51,
Fuel Injector.>
Step Check Yes No
15WRX_STI_US_EN.book 189 ージ 20  
EN(w/o STI)(diag)-190
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BK:DTC P0191 FUEL RAIL PRESSURE SENSOR "A" CIRCUIT RANGE/PER-
FORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-87, DTC P0191 FUEL RAIL PRESSURE SENSOR "A"
CIRCUIT RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
213
E162
E158B:
E159C:
E162
1
2
3
C27
B6
C19
EN-10324
ECM
FUEL
PRESSURE
SENSOR
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 190 ージ 20  
EN(w/o STI)(diag)-191
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Fuel Rail Pressure A»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Fuel Rail
Pressure A» 2,500 kPa (25.49
kgf/cm
2
, 362.6 psi) or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK FUEL PRESSURE SENSOR POWER
SUPPLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the fuel
pressure sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between fuel pressure
sensor connector and engine ground.
Connector & terminal
(E162) No. 3 (+) — Engine ground (–):
Is the voltage 4.5 V or more? Go to step 3. Go to step 6.
3 CHECK FUEL PRESSURE SENSOR SIG-
NAL.
1) Connect all connectors.
2) Start the engine.
3) Read the value of «Fuel Rail Pressure A»
when idling using the Subaru Select Monitor or
a general scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
4) Measure the voltage between ECM connec-
tors.
Connector & terminal
(E158) No. 6 (+) — (E159) No. 27 (–):
When the value of «Fuel Rail
Pressure A» during idling is
approx. 4,000 kPa (40.79
kgf/cm
2
, 580.2 psi), is the
voltage 0.75 — 1.5 V?
Repair the poor
contact of ECM
connector.
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
FUEL PRESSURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
fuel pressure sensor.
3) Measure the resistance of harness between
ECM connector and fuel pressure sensor con-
nector.
Connector & terminal
(E159) No. 27 — (E162) No. 1:
(E158) No. 6 — (E162) No. 2:
Is the resistance less than 1 Ω? Go to step 5. Repair the open
circuit in harness
between ECM con-
nector and fuel
pressure sensor
connector.
15WRX_STI_US_EN.book 191 ージ 20  
EN(w/o STI)(diag)-192
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
5 CHECK HARNESS BETWEEN ECM AND
FUEL PRESSURE SENSOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 6 — Engine ground:
(E159) No. 27 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the fuel
pressure sensor.
<Ref. to FU(w/o
STI)-71, Fuel Pres-
sure Sensor.>
Repair the ground
short circuit of har-
ness between
ECM connector
and fuel pressure
sensor connector.
6 CHECK HARNESS BETWEEN ECM AND
FUEL PRESSURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and fuel pressure sensor con-
nector.
Connector & terminal
(E159) No. 19 — (E162) No. 3:
Is the resistance less than 1 Ω? Go to step 7. Repair the open
circuit in harness
between ECM con-
nector and fuel
pressure sensor
connector.
7 CHECK HARNESS BETWEEN ECM AND
FUEL PRESSURE SENSOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E159) No. 19 — Engine ground:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of ECM
connector.
Repair the ground
short circuit of har-
ness between
ECM connector
and fuel pressure
sensor connector.
Step Check Yes No
15WRX_STI_US_EN.book 192 ージ 20  
EN(w/o STI)(diag)-193
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BL:DTC P0192 FUEL RAIL PRESSURE SENSOR CIRCUIT LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-88, DTC P0192 FUEL RAIL PRESSURE SENSOR CIR-
CUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
213
E162
E158B:
E159C:
E162
1
2
3
C27
B6
C19
EN-10324
ECM
FUEL
PRESSURE
SENSOR
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 193 ージ 20  
EN(w/o STI)(diag)-194
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Fuel Rail Pressure A»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Fuel Rail
Pressure A» approx. 0 kPa (0
kgf/cm
2
, 0 psi)?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND
FUEL PRESSURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
fuel pressure sensor.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 6 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the fuel
pressure sensor.
<Ref. to FU(w/o
STI)-71, Fuel Pres-
sure Sensor.>
Repair the ground
short circuit of har-
ness between
ECM connector
and fuel pressure
sensor connector.
15WRX_STI_US_EN.book 194 ージ 20  
EN(w/o STI)(diag)-195
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BM:DTC P0193 FUEL RAIL PRESSURE SENSOR CIRCUIT HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-89, DTC P0193 FUEL RAIL PRESSURE SENSOR CIR-
CUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
213
E162
E158B:
E159C:
E162
1
2
3
C27
B6
C19
EN-10324
ECM
FUEL
PRESSURE
SENSOR
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 195 ージ 20  
EN(w/o STI)(diag)-196
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Fuel Rail Pressure A»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Fuel Rail
Pressure A» 30,000 kPa
(305.9 kgf/cm
2
, 4,351 psi) or
more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and fuel pres-
sure sensor connector.
Is there poor contact of the
ECM or fuel pressure sensor
connector?
Repair the poor
contact of the ECM
or fuel pressure
sensor connector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
FUEL PRESSURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
fuel pressure sensor.
3) Measure the resistance of harness between
ECM connector and fuel pressure sensor con-
nector.
Connector & terminal
(E159) No. 27 — (E162) No. 1:
(E158) No. 6 — (E162) No. 2:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit in harness
between ECM con-
nector and fuel
pressure sensor
connector.
4 CHECK HARNESS BETWEEN ECM AND
FUEL PRESSURE SENSOR CONNECTOR.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E158) No. 6 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and fuel
pressure sensor
connector.
Replace the fuel
pressure sensor.
<Ref. to FU(w/o
STI)-71, Fuel Pres-
sure Sensor.>
15WRX_STI_US_EN.book 196 ージ 20  
EN(w/o STI)(diag)-197
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BN:DTC P0196 ENGINE OIL TEMPERATURE SENSOR CIRCUIT RANGE/PER-
FORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-90, DTC P0196 ENGINE OIL TEMPERATURE SEN-
SOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Hard to start
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
E158B:
E159C:
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
12
E75
E75
1
2
C27
B2
EN-10325
ECM
ENGINE OIL
TEMPERATURE
SENSOR
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 197 ージ 20  
EN(w/o STI)(diag)-198
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK ENGINE OIL TEMPERATURE SEN-
SOR.
1) Disconnect the connectors from the engine
oil temperature sensor.
2) Measure the resistance between engine oil
temperature sensor terminals when the engine
is cold and after warmed up.
Terminals
No. 1 — No. 2:
Is the resistance of engine oil
temperature sensor different
between when engine is cold
and after warmed up?
Repair the poor
contact of ECM
connector.
Replace the
engine oil tempera-
ture sensor. <Ref.
to FU(w/o STI)-96,
Engine Oil Temper-
ature Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 198 ージ 20  
EN(w/o STI)(diag)-199
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BO:DTC P0197 ENGINE OIL TEMPERATURE SENSOR LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-92, DTC P0197 ENGINE OIL TEMPERATURE SEN-
SOR LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Hard to start
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
E158B:
E159C:
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
12
E75
E75
1
2
C27
B2
EN-10325
ECM
ENGINE OIL
TEMPERATURE
SENSOR
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 199 ージ 20  
EN(w/o STI)(diag)-200
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Oil Temperature» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oil Tempera-
ture» 150°C (302°F) or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND EN-
GINE OIL TEMPERATURE SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM
and engine oil temperature sensor.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the
engine oil tempera-
ture sensor. <Ref.
to FU(w/o STI)-96,
Engine Oil Temper-
ature Sensor.>
Repair the short
circuit to ground in
the harness
between the ECM
connector and
engine oil tempera-
ture sensor con-
nector.
15WRX_STI_US_EN.book 200 ージ 20  
EN(w/o STI)(diag)-201
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BP:DTC P0198 ENGINE OIL TEMPERATURE SENSOR HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-93, DTC P0198 ENGINE OIL TEMPERATURE SEN-
SOR HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Hard to start
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
E158B:
E159C:
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
12
E75
E75
1
2
C27
B2
EN-10325
ECM
ENGINE OIL
TEMPERATURE
SENSOR
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 201 ージ 20  
EN(w/o STI)(diag)-202
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Oil Temperature» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oil Tempera-
ture» –40°C (–40°F) or less?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK FOR POOR CONTACT.
Check for poor contact between the ECM and
engine oil temperature sensor connectors.
Is there poor contact of the
ECM or engine oil temperature
sensor connectors?
Repair the poor
contact of ECM or
engine oil tempera-
ture sensor con-
nector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND EN-
GINE OIL TEMPERATURE SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM
and engine oil temperature sensor.
3) Measure the resistance of the harness
between the ECM connector and engine oil
temperature sensor connector.
Connector & terminal
(E159) No. 27 — (E75) No. 1:
(E158) No. 2 — (E75) No. 2:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit in the har-
ness between
ECM connector
and engine oil tem-
perature sensor
connector.
4 CHECK HARNESS BETWEEN ECM AND EN-
GINE OIL TEMPERATURE SENSOR CON-
NECTOR.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E158) No. 2 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
harness between
ECM connector
and engine oil tem-
perature sensor
connector.
Replace the
engine oil tempera-
ture sensor. <Ref.
to FU(w/o STI)-96,
Engine Oil Temper-
ature Sensor.>
15WRX_STI_US_EN.book 202 ージ 20  
EN(w/o STI)(diag)-203
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BQ:DTC P0222 THROTTLE/PEDAL POSITION SENSOR/SWITCH “B” CIRCUIT
LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-94, DTC P0222 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “B” CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
Engine stalls.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 203 ージ 20  
EN(w/o STI)(diag)-204
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 18 — Engine ground:
(E158) No. 29 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 2. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
ECM
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B225
14
17
15
16
B550
215
317
B220
1011
E57
B17
B29
B18
B30
6
5
3
2
4
1
C1
C2
A39
A11
B225B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10800
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
BATTERY
ELECTRONIC
THROTTLE
CONTROL
MAIN RELAY
FUSE HOLDER
ELECTRONIC
THROTTLE CONTROL
RELAY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 204 ージ 20  
EN(w/o STI)(diag)-205
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 4 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the elec-
tronic throttle con-
trol. <Ref. to FU(w/
o STI)-15, Throttle
Body.>
Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
Replace the ECM if
defective. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
Step Check Yes No
15WRX_STI_US_EN.book 205 ージ 20  
EN(w/o STI)(diag)-206
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BR:DTC P0223 THROTTLE/PEDAL POSITION SENSOR/SWITCH “B” CIRCUIT
HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-95, DTC P0223 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “B” CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
Engine stalls.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 206 ージ 20  
EN(w/o STI)(diag)-207
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance of harness between
ECM connector and electronic throttle control
connector.
Connector & terminal
(E158) No. 29 — (E57) No. 4:
(E158) No. 30 — (E57) No. 3:
Is the resistance less than 1 Ω? Go to step 2. Repair the open
circuit of harness
between ECM con-
nector and elec-
tronic throttle
control connector.
ECM
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B225
14
17
15
16
B550
215
317
B220
1011
E57
B17
B29
B18
B30
6
5
3
2
4
1
C1
C2
A39
A11
B225B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10800
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
BATTERY
ELECTRONIC
THROTTLE
CONTROL
MAIN RELAY
FUSE HOLDER
ELECTRONIC
THROTTLE CONTROL
RELAY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 207 ージ 20  
EN(w/o STI)(diag)-208
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 3 — Engine ground:
Is the resistance less than 5 Ω? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
ECM connector
Poor contact of
coupling connector
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 4 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(E158) No. 18 — (E158) No. 29:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to FU(w/o
STI)-15, Throttle
Body.>
Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Step Check Yes No
15WRX_STI_US_EN.book 208 ージ 20  
EN(w/o STI)(diag)-209
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BS:DTC P0230 FUEL PUMP PRIMARY CIRCUIT
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-96, DTC P0230 FUEL PUMP PRIMARY CIRCUIT, Di-
agnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B97
1234 56789
10 11 12 13 14 15 16 17 18 19 20
EN-10801
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
R122
63451
2
B134
R58
4
3
6
7
5
B97
R1
B220
21
1
R58
34
12
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
R122
6
2
3
4
5
40
44
ECM
FUEL PUMP CU
BATTERY
FUEL PUMP RELAY
M/B No. 11
FUEL PUMP
(BROWN)
15WRX_STI_US_EN.book 209 ージ 20  
EN(w/o STI)(diag)-210
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK POWER SUPPLY CIRCUIT TO FUEL
PUMP CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel pump
control unit.
3) Turn the ignition switch to ON.
4) Measure the voltage between fuel pump
control unit connector and engine ground.
Connector & terminal
(R122) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the power
supply circuit.
NOTE:
In this case, repair
the following item:
Open circuit or
short circuit to
ground in harness
between fuel pump
relay connector
and fuel pump con-
trol unit connector
Poor contact of
fuel pump control
unit connector
Poor contact of
fuel pump relay
connector
Poor contact of
coupling connector
2 CHECK GROUND CIRCUIT OF FUEL PUMP
CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between
fuel pump control unit connector and engine
ground.
Connector & terminal
(R122) No. 4 — Engine ground:
Is the resistance less than 5 Ω? Go to step 3. Repair the open
circuit between fuel
pump control unit
connector and
engine ground.
3 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
1) Disconnect the connector from fuel pump.
2) Measure the resistance of harness between
fuel pump control unit and fuel pump connector.
Connector & terminal
(R122) No. 5 — (R58) No. 4:
(R122) No. 6 — (R58) No. 3:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit in harness
between fuel pump
control unit con-
nector and fuel
pump connector.
4 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
Measure the resistance between fuel pump
control unit connector and engine ground.
Connector & terminal
(R122) No. 5 — Engine ground:
(R122) No. 6 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
fuel pump control
unit connector and
fuel pump connec-
tor.
5 CHECK HARNESS BETWEEN ECM AND
FUEL PUMP CONTROL UNIT CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness between
ECM connector and fuel pump control unit con-
nector.
Connector & terminal
(B134) No. 40 — (R122) No. 2:
(B134) No. 44 — (R122) No. 3:
Is the resistance less than 1 Ω? Go to step 6. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and fuel pump con-
trol unit connector
Poor contact of
coupling connector
15WRX_STI_US_EN.book 210 ージ 20  
EN(w/o STI)(diag)-211
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK HARNESS BETWEEN ECM AND
FUEL PUMP CONTROL UNIT CONNECTOR.
Measure the resistance between fuel pump
control unit connector and engine ground.
Connector & terminal
(R122) No. 2 — Engine ground:
(R122) No. 3 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 7. Repair the short
circuit to ground in
harness between
ECM connector
and fuel pump con-
trol unit connector.
7 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and fuel pump
control unit connector.
Is there poor contact of ECM or
fuel pump control unit connec-
tor?
Repair the poor
contact of ECM or
fuel pump control
unit connector.
Go to step 8.
8 CHECK EXPERIENCE OF RUNNING OUT OF
FUEL.
Has the vehicle experienced
running out of fuel?
Finish the diagno-
sis.
NOTE:
DTC may be re-
corded as a result
of fuel pump idling
while running out
of fuel.
Replace the fuel
pump control unit.
<Ref. to FU(w/o
STI)-145, Fuel
Pump Control
Unit.>
Step Check Yes No
15WRX_STI_US_EN.book 211 ージ 20  
EN(w/o STI)(diag)-212
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BT:DTC P023F FUEL PUMP SECONDARY CIRCUIT/OPEN
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-97, DTC P023F FUEL PUMP SECONDARY CIRCUIT/
OPEN, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HIGH-PRESSURE FUEL PUMP.
Check the high-pressure fuel pump. <Ref. to
FU(w/o STI)-82, INSPECTION, High Pressure
Fuel Pump.>
Is the high-pressure fuel pump
normal?
Go to step 2. Replace the high-
pressure fuel
pump. <Ref. to
FU(w/o STI)-74,
High Pressure
Fuel Pump.>
12
E160
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
E158
E160
1
2
10
22
EN-10802
ECM
HIGH-PRESSURE
FUEL PUMP
(BLACK)
15WRX_STI_US_EN.book 212 ージ 20  
EN(w/o STI)(diag)-213
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK HARNESS BETWEEN ECM AND
HIGH-PRESSURE FUEL PUMP CONNEC-
TOR.
1) Disconnect the connector from ECM and
high-pressure fuel pump.
2) Measure the resistance of harness between
ECM connector and high-pressure fuel pump
connector.
Connector & terminal
(E158) No. 10 — (E160) No. 1:
(E158) No. 22 — (E160) No. 2:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit in harness
between ECM con-
nector and high-
pressure fuel
pump connector.
3 CHECK HARNESS BETWEEN ECM AND
HIGH-PRESSURE FUEL PUMP CONNEC-
TOR.
Measure the resistance between high-pressure
fuel pump connector and engine ground.
Connector & terminal
(E160) No. 1 — Engine ground:
(E160) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of ECM
connector.
Repair the short
circuit to ground in
harness between
ECM connector
and high-pressure
fuel pump connec-
tor.
Step Check Yes No
15WRX_STI_US_EN.book 213 ージ 20  
EN(w/o STI)(diag)-214
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BU:DTC P0244 TURBO/SUPER CHARGER WASTEGATE SOLENOID “A”
RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-98, DTC P0244 TURBO/SUPER CHARGER WASTE-
GATE SOLENOID “A” RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK WASTEGATE ACTUATOR PIPING
AND WASTEGATE CONTROL SOLENOID
VALVE PIPING.
Are there any damage or dis-
connection of hose in waste-
gate actuator piping or
wastegate control solenoid
valve piping?
Connect the
wastegate actuator
pipe or wastegate
control solenoid
valve pipe properly.
If defective,
replace the hose.
Replace the waste-
gate control sole-
noid valve. <Ref. to
FU(w/o STI)-123,
Wastegate Control
Solenoid Valve.>
15WRX_STI_US_EN.book 214 ージ 20  
EN(w/o STI)(diag)-215
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BV:DTC P0245 TURBO/SUPER CHARGER WASTEGATE SOLENOID “A” LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-100, DTC P0245 TURBO/SUPER CHARGER WASTE-
GATE SOLENOID “A” LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 11 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Go to step 3.
12
E64
4
E3
B22
EN-10803
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
1
2
E159
11
E64
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
ECM
SBF-7
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
(GRAY)
WASTEGATE CONTROL
SOLENOID VALVE
MAIN RELAY
BATTERY
FUSE HOLDER
15WRX_STI_US_EN.book 215 ージ 20  
EN(w/o STI)(diag)-216
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
3 CHECK POWER SUPPLY TO WASTEGATE
CONTROL SOLENOID VALVE.
Measure the voltage between wastegate con-
trol solenoid valve connector and engine
ground.
Connector & terminal
(E64) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the power
supply circuit.
4 CHECK HARNESS BETWEEN ECM AND
WASTEGATE CONTROL SOLENOID VALVE
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
wastegate control solenoid valve.
3) Measure the resistance between wastegate
control solenoid valve connector and engine
ground.
Connector & terminal
(E64) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair ground
short circuit of har-
ness between
ECM connector
and wastegate
control solenoid
valve connector.
5 CHECK HARNESS BETWEEN ECM AND
WASTEGATE CONTROL SOLENOID VALVE
CONNECTOR.
Measure the resistance of harness between
ECM connector and wastegate control solenoid
valve connector.
Connector & terminal
(E159) No. 11 — (E64) No. 2:
Is the resistance less than 1 Ω? Go to step 6. Repair open circuit
in harness
between ECM con-
nector and waste-
gate control
solenoid valve con-
nector.
6 CHECK WASTEGATE CONTROL SOLE-
NOID VALVE.
1) Remove the wastegate control solenoid
valve.
2) Measure the resistance between wastegate
control solenoid valve terminals.
Terminals
No. 1 — No. 2:
Is the resistance 10 — 100 Ω? Repair poor con-
tact of wastegate
control solenoid
valve connector.
Replace the waste-
gate control sole-
noid valve. <Ref. to
FU(w/o STI)-123,
Wastegate Control
Solenoid Valve.>
Step Check Yes No
15WRX_STI_US_EN.book 216 ージ 20  
EN(w/o STI)(diag)-217
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BW:DTC P0246 TURBO/SUPER CHARGER WASTEGATE SOLENOID “A” HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-101, DTC P0246 TURBO/SUPER CHARGER WASTE-
GATE SOLENOID “A” HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
WASTEGATE CONTROL SOLENOID VALVE
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
wastegate control solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 11 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair short cir-
cuit to power in
harness between
ECM connector
and wastegate
control solenoid
valve connector.
Go to step 2.
12
E64
4
E3
B22
EN-10803
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
1
2
E159
11
E64
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
ECM
SBF-7
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
(GRAY)
WASTEGATE CONTROL
SOLENOID VALVE
MAIN RELAY
BATTERY
FUSE HOLDER
15WRX_STI_US_EN.book 217 ージ 20  
EN(w/o STI)(diag)-218
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK WASTEGATE CONTROL SOLE-
NOID VALVE.
1) Turn the ignition switch to OFF.
2) Measure the resistance between wastegate
control solenoid valve terminals.
Terminals
No. 1 — No. 2:
Is the resistance less than 1 Ω? Replace the waste-
gate control sole-
noid valve. <Ref. to
FU(w/o STI)-123,
Wastegate Control
Solenoid Valve.>
Repair the poor
contact of ECM
connector.
Step Check Yes No
15WRX_STI_US_EN.book 218 ージ 20  
EN(w/o STI)(diag)-219
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BX:DTC P0300 RANDOM/MULTIPLE CYLINDER MISFIRE DETECTED
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
Immediately at fault recognition (A misfire which could damage catalyst occurs.)
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-101, DTC P0300 RANDOM/MULTIPLE CYLINDER
MISFIRE DETECTED, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
Rough driving
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 219 ージ 20  
EN(w/o STI)(diag)-220
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
2
E6
E5
E17
E16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
2
1
E5
B11
B23
B35
EN-10794
2
1
E16
2
1
E6
2
1
E17
B47
B12
B24
B36
B48
C18
C17
C10
A35
A47
16
15
E3
B22
C26
C25
B134A:
E158B:
C: E159
ECM
FUEL INJECTOR No. 4
FUEL INJECTOR No. 3
FUEL INJECTOR No. 2
FUEL INJECTOR No. 1
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 220 ージ 20  
EN(w/o STI)(diag)-221
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from all fuel injec-
tors.
3) Measure the resistance between all fuel
injector connectors and engine ground.
Connector & terminal
#1 (E5) No. 1 — Engine ground:
#1 (E5) No. 2 — Engine ground:
#2 (E16) No. 1 — Engine ground:
#2 (E16) No. 2 — Engine ground:
#3 (E6) No. 1 — Engine ground:
#3 (E6) No. 2 — Engine ground:
#4 (E17) No. 1 — Engine ground:
#4 (E17) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 2. Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
2 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance of harness between
ECM connector and fuel injector connector on
all cylinders.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
3 CHECK FUEL INJECTOR.
Check all fuel injectors. <Ref. to FU(w/o STI)-
70, INSPECTION, Fuel Injector.>
Are fuel injectors OK? Go to step 4. Replace the faulty
fuel injector. <Ref.
to FU(w/o STI)-51,
Fuel Injector.>
4 CHECK INSTALLATION CONDITION OF
CAMSHAFT POSITION SENSOR/CRANK-
SHAFT POSITION SENSOR.
Is the camshaft position sensor
or crankshaft position sensor
loosely installed?
Tighten the cam-
shaft position sen-
sor or crankshaft
position sensor.
<Ref. to FU(w/o
STI)-104, INSTAL-
LATION, Cam-
shaft Position
Sensor.> <Ref. to
FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
Go to step 5.
5 CHECK CRANKSHAFT POSITION SENSOR
PLATE.
Is the crankshaft position sen-
sor plate rusted or does it have
broken teeth?
Replace the crank-
shaft position sen-
sor plate. <Ref. to
ME(w/o STI)-260,
Cylinder Block.>
Go to step 6.
6 CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Turn the crankshaft using ST, and align the
alignment mark on crank sprocket with align-
ment mark on cylinder block.
ST 18252AA000 CRANKSHAFT
SOCKET
Is the timing chain dislocated
from its proper position?
Correct the instal-
lation condition of
timing chain. <Ref.
to ME(w/o STI)-
116, Timing Chain
Assembly.>
Go to step 7.
15WRX_STI_US_EN.book 221 ージ 20  
EN(w/o STI)(diag)-222
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
7 CHECK FUEL LEVEL. Is the fuel meter indication
higher than the “Lower” level?
Go to step 8. Refill the fuel so
that the fuel meter
indication is higher
than the “Lower”
level, and proceed
to the next step. Go
to step 8.
8 CHECK STATUS OF MALFUNCTION INDI-
CATOR LIGHT.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, Clear Memory Mode.>
2) Start the engine, and drive the vehicle 10
minutes or more.
Does the malfunction indicator
light illuminate or blink?
Go to step 10. Go to step 9.
9 CHECK CAUSE OF MISFIRE. Was the cause of misfire identi-
fied when the engine is run-
ning?
Finish diagnostics
operation, if the
engine has no
abnormality.
Repair the poor
contact of connec-
tor.
NOTE:
In this case, repair
the following item:
Poor contact of
ignition coil con-
nector
Poor contact of
fuel injector con-
nector on faulty
cylinders
Poor contact of
ECM connector
Poor contact of
coupling connector
10 CHECK AIR INTAKE SYSTEM. Is there any fault in air intake
system?
Repair the air
intake system.
NOTE:
Check the follow-
ing items.
Are there air
leaks or air suction
caused by loose or
dislocated nuts
and bolts?
Are there cracks
or any disconnec-
tion of hoses?
Go to step 11.
11 CHECK ALL CYLINDERS. Is there a fault in any cylinder? Repair or replace
the faulty part of
the faulty cylinder.
NOTE:
Check the follow-
ing items.
Spark plug
Ignition coil
Fuel injector
Compression ra-
tio
Skipping timing
chain teeth
Go to DTC P0171.
<Ref. to EN(w/o
STI)(diag)-185,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
Step Check Yes No
15WRX_STI_US_EN.book 222 ージ 20  
EN(w/o STI)(diag)-223
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
BY:DTC P0301 CYLINDER 1 MISFIRE DETECTED
NOTE:
For the diagnostic procedure, refer to DTC P0304. <Ref. to EN(w/o STI)(diag)-224, DTC P0304 CYLINDER
4 MISFIRE DETECTED, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
BZ:DTC P0302 CYLINDER 2 MISFIRE DETECTED
NOTE:
For the diagnostic procedure, refer to DTC P0304. <Ref. to EN(w/o STI)(diag)-224, DTC P0304 CYLINDER
4 MISFIRE DETECTED, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
CA:DTC P0303 CYLINDER 3 MISFIRE DETECTED
NOTE:
For the diagnostic procedure, refer to DTC P0304. <Ref. to EN(w/o STI)(diag)-224, DTC P0304 CYLINDER
4 MISFIRE DETECTED, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
15WRX_STI_US_EN.book 223 ージ 20  
EN(w/o STI)(diag)-224
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CB:DTC P0304 CYLINDER 4 MISFIRE DETECTED
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
Immediately at fault recognition (A misfire which could damage catalyst occurs.)
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-106, DTC P0304 CYLINDER 4 MISFIRE DETECTED,
Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
Rough driving
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 224 ージ 20  
EN(w/o STI)(diag)-225
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
2
E6
E5
E17
E16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
2
1
E5
B11
B23
B35
EN-10794
2
1
E16
2
1
E6
2
1
E17
B47
B12
B24
B36
B48
C18
C17
C10
A35
A47
16
15
E3
B22
C26
C25
B134A:
E158B:
C: E159
ECM
FUEL INJECTOR No. 4
FUEL INJECTOR No. 3
FUEL INJECTOR No. 2
FUEL INJECTOR No. 1
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 225 ージ 20  
EN(w/o STI)(diag)-226
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel injector
on faulty cylinders.
3) Measure the resistance between fuel injec-
tor connector and engine ground on faulty cylin-
ders.
Connector & terminal
#1 (E5) No. 1 — Engine ground:
#1 (E5) No. 2 — Engine ground:
#2 (E16) No. 1 — Engine ground:
#2 (E16) No. 2 — Engine ground:
#3 (E6) No. 1 — Engine ground:
#3 (E6) No. 2 — Engine ground:
#4 (E17) No. 1 — Engine ground:
#4 (E17) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 2. Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
2 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance of harness between
ECM connector and fuel injector connector on
faulty cylinders.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
3 CHECK FUEL INJECTOR.
Check the fuel injector on faulty cylinder. <Ref.
to FU(w/o STI)-70, INSPECTION, Fuel Injec-
tor.>
Are fuel injectors OK? Go to step 4. Replace the faulty
fuel injector. <Ref.
to FU(w/o STI)-51,
Fuel Injector.>
4 CHECK INSTALLATION CONDITION OF
CAMSHAFT POSITION SENSOR/CRANK-
SHAFT POSITION SENSOR.
Is the camshaft position sensor
or crankshaft position sensor
loosely installed?
Tighten the cam-
shaft position sen-
sor or crankshaft
position sensor.
<Ref. to FU(w/o
STI)-104, INSTAL-
LATION, Cam-
shaft Position
Sensor.> <Ref. to
FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
Go to step 5.
5 CHECK CRANKSHAFT POSITION SENSOR
PLATE.
Is the crankshaft position sen-
sor plate rusted or does it have
broken teeth?
Replace the crank-
shaft position sen-
sor plate. <Ref. to
ME(w/o STI)-260,
Cylinder Block.>
Go to step 6.
6 CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Turn the crankshaft using ST, and align the
alignment mark on crank sprocket with align-
ment mark on cylinder block.
ST 18252AA000 CRANKSHAFT
SOCKET
Is the timing chain dislocated
from its proper position?
Correct the instal-
lation condition of
timing chain. <Ref.
to ME(w/o STI)-
116, Timing Chain
Assembly.>
Go to step 7.
15WRX_STI_US_EN.book 226 ージ 20  
EN(w/o STI)(diag)-227
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
7 CHECK FUEL LEVEL. Is the fuel meter indication
higher than the “Lower” level?
Go to step 8. Refill the fuel so
that the fuel meter
indication is higher
than the “Lower”
level, and proceed
to the next step. Go
to step 8.
8 CHECK STATUS OF MALFUNCTION INDI-
CATOR LIGHT.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, Clear Memory Mode.>
2) Start the engine, and drive the vehicle 10
minutes or more.
Does the malfunction indicator
light illuminate or blink?
Go to step 10. Go to step 9.
9 CHECK CAUSE OF MISFIRE. Was the cause of misfire identi-
fied when the engine is run-
ning?
Finish diagnostics
operation, if the
engine has no
abnormality.
Repair the poor
contact of connec-
tor.
NOTE:
In this case, repair
the following item:
Poor contact of
ignition coil con-
nector
Poor contact of
fuel injector con-
nector on faulty
cylinders
Poor contact of
ECM connector
Poor contact of
coupling connector
10 CHECK AIR INTAKE SYSTEM. Is there any fault in air intake
system?
Repair the air
intake system.
NOTE:
Check the follow-
ing items.
Are there air
leaks or air suction
caused by loose or
dislocated nuts
and bolts?
Are there cracks
or any disconnec-
tion of hoses?
Go to step 11.
11 CHECK CYLINDER. Is there any fault in the cylin-
der?
Repair or replace
faulty parts.
NOTE:
Check the follow-
ing items.
Spark plug
Ignition coil
Fuel injector
Compression ra-
tio
Skipping timing
chain teeth
Go to DTC P0171.
<Ref. to EN(w/o
STI)(diag)-185,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
Step Check Yes No
15WRX_STI_US_EN.book 227 ージ 20  
EN(w/o STI)(diag)-228
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CC:DTC P0327 KNOCK SENSOR 1 CIRCUIT LOW (BANK 1 OR SINGLE SEN-
SOR)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-107, DTC P0327 KNOCK SENSOR 1 CIRCUIT LOW
(BANK 1 OR SINGLE SENSOR), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Poor driving performance
Knocking occurs
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
KNOCK SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(E158) No. 14 — (E159) No. 27:
Is the resistance less than 500
kΩ?
Go to step 2. Go to step 3.
E14
EN-10804
E158B:
E159C:
1
2
C27
B14
E48
1
2B26
E14 E48
12
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
ECM
(GRAY)
(BLACK)
KNOCK SENSOR LH
KNOCK SENSOR RH
15WRX_STI_US_EN.book 228 ージ 20  
EN(w/o STI)(diag)-229
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from the knock
sensor.
2) Measure the resistance between knock
sensor connectors.
Terminals
No. 1 — No. 2:
Is the resistance less than 500
kΩ?
Replace the knock
sensor. <Ref. to
FU(w/o STI)-111,
Knock Sensor.>
Repair the short
circuit to ground in
harness between
ECM connector
and knock sensor
connector.
NOTE:
The harness be-
tween both con-
nectors are
shielded. Remove
the shield and re-
pair the short cir-
cuit of harness.
3 CHECK INPUT SIGNAL OF ECM.
1) Connect the ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E158) No. 14 (+) — Engine ground (–):
Is the voltage 2 V or more? Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
Repair the short
circuit to ground in
harness between
ECM connector
and knock sensor
connector.
NOTE:
The harness be-
tween both con-
nectors are
shielded. Remove
the shield and re-
pair the short cir-
cuit of harness.
Step Check Yes No
15WRX_STI_US_EN.book 229 ージ 20  
EN(w/o STI)(diag)-230
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CD:DTC P0328 KNOCK SENSOR 1 CIRCUIT HIGH (BANK 1 OR SINGLE SEN-
SOR)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-108, DTC P0328 KNOCK SENSOR 1 CIRCUIT HIGH
(BANK 1 OR SINGLE SENSOR), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Poor driving performance
Knocking occurs
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
KNOCK SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(E158) No. 14 — (E159) No. 27:
Is the resistance 600 kΩ or
more?
Go to step 2. Repair the poor
contact of ECM
connector.
E14
EN-10804
E158B:
E159C:
1
2
C27
B14
E48
1
2B26
E14 E48
12
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
ECM
(GRAY)
(BLACK)
KNOCK SENSOR LH
KNOCK SENSOR RH
15WRX_STI_US_EN.book 230 ージ 20  
EN(w/o STI)(diag)-231
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from the knock
sensor.
2) Measure the resistance between knock
sensor terminals.
Terminals
No. 1 — No. 2:
Is the resistance 600 kΩ or
more?
Replace the knock
sensor. <Ref. to
FU(w/o STI)-111,
Knock Sensor.>
Repair the open
circuit in harness
between ECM con-
nector and knock
sensor connector.
Step Check Yes No
15WRX_STI_US_EN.book 231 ージ 20  
EN(w/o STI)(diag)-232
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CE:DTC P0332 KNOCK SENSOR 2 CIRCUIT LOW (BANK 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-109, DTC P0332 KNOCK SENSOR 2 CIRCUIT LOW
(BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Driving performance problem
Knocking occurs
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
KNOCK SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(E158) No. 26 — (E159) No. 27:
Is the resistance less than 500
kΩ?
Go to step 2. Go to step 3.
E14
EN-10804
E158B:
E159C:
1
2
C27
B14
E48
1
2B26
E14 E48
12
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
ECM
(GRAY)
(BLACK)
KNOCK SENSOR LH
KNOCK SENSOR RH
15WRX_STI_US_EN.book 232 ージ 20  
EN(w/o STI)(diag)-233
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from the knock
sensor.
2) Measure the resistance between knock
sensor connectors.
Terminals
No. 1 — No. 2:
Is the resistance less than 500
kΩ?
Replace the knock
sensor. <Ref. to
FU(w/o STI)-111,
Knock Sensor.>
Repair the short
circuit to ground in
harness between
ECM connector
and knock sensor
connector.
NOTE:
The harness be-
tween both con-
nectors are
shielded. Remove
the shield and re-
pair the short cir-
cuit of harness.
3 CHECK INPUT SIGNAL OF ECM.
1) Connect the ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E158) No. 26 (+) — Engine ground (–):
Is the voltage 2 V or more? Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
Repair the short
circuit to ground in
harness between
ECM connector
and knock sensor
connector.
NOTE:
The harness be-
tween both con-
nectors are
shielded. Remove
the shield and re-
pair the short cir-
cuit of harness.
Step Check Yes No
15WRX_STI_US_EN.book 233 ージ 20  
EN(w/o STI)(diag)-234
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CF:DTC P0333 KNOCK SENSOR 2 CIRCUIT HIGH (BANK 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-110, DTC P0333 KNOCK SENSOR 2 CIRCUIT HIGH
(BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Driving performance problem
Knocking occurs
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
KNOCK SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(E158) No. 26 — (E159) No. 27:
Is the resistance 600 kΩ or
more?
Go to step 2. Repair the poor
contact of ECM
connector.
E14
EN-10804
E158B:
E159C:
1
2
C27
B14
E48
1
2B26
E14 E48
12
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
ECM
(GRAY)
(BLACK)
KNOCK SENSOR LH
KNOCK SENSOR RH
15WRX_STI_US_EN.book 234 ージ 20  
EN(w/o STI)(diag)-235
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from the knock
sensor.
2) Measure the resistance between knock
sensor terminals.
Terminals
No. 1 — No. 2:
Is the resistance 600 kΩ or
more?
Replace the knock
sensor. <Ref. to
FU(w/o STI)-111,
Knock Sensor.>
Repair the open
circuit in harness
between ECM con-
nector and knock
sensor connector.
Step Check Yes No
15WRX_STI_US_EN.book 235 ージ 20  
EN(w/o STI)(diag)-236
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CG:DTC P0335 CRANKSHAFT POSITION SENSOR “A” CIRCUIT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-111, DTC P0335 CRANKSHAFT POSITION SENSOR
“A” CIRCUIT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
4
E3
B22
EN-10805
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
1
2
E158
19
E10
B22
12
3
4
5678
9
10 11 12
1413 15 16
E10
213
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
3
31
ECM
SBF-7
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
(BLACK)
CRANKSHAFT
POSITION SENSOR
MAIN RELAY
BATTERY
FUSE HOLDER
15WRX_STI_US_EN.book 236 ージ 20  
EN(w/o STI)(diag)-237
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK POWER SUPPLY OF CRANKSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the crank-
shaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit or
short circuit to
ground in harness
between main re-
lay connector and
crankshaft posi-
tion sensor con-
nector
Poor contact of
coupling connector
2 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and crankshaft position sensor connec-
tor.
Connector & terminal
(E158) No. 19 — (E10) No. 2:
(E158) No. 31 — (E10) No. 3:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit in the har-
ness between the
ECM connector
and crankshaft
position sensor
connector.
3 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
Measure the resistance between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 2 — Engine ground:
(E10) No. 3 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair short cir-
cuit to ground in
harness between
ECM connector
and crankshaft
position sensor
connector.
4 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
Measure the voltage between crankshaft posi-
tion sensor connector and engine ground.
Connector & terminal
(E10) No. 2 (+) — Engine ground (–):
(E10) No. 3 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and crank-
shaft position
sensor connector.
Go to step 5.
5 CHECK CONDITION OF CRANKSHAFT PO-
SITION SENSOR.
Is the crankshaft position sen-
sor installation bolt tightened
securely?
Go to step 6. Tighten the crank-
shaft position sen-
sor installation bolt
securely. <Ref. to
FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
6 CHECK CRANKSHAFT POSITION SENSOR.
Check waveform of crankshaft position sensor.
<Ref. to EN(w/o STI)(diag)-20, Engine Control
Module (ECM) I/O Signal.>
Is there any abnormality in
waveform?
Replace the crank-
shaft position sen-
sor. <Ref. to FU(w/
o STI)-103, Cam-
shaft Position Sen-
sor.>
Repair the follow-
ing item.
Poor contact of
ECM connector
Poor contact of
crankshaft posi-
tion sensor con-
nector
Poor contact of
coupling connector
15WRX_STI_US_EN.book 237 ージ 20  
EN(w/o STI)(diag)-238
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CH:DTC P0336 CRANKSHAFT POSITION SENSOR “A” CIRCUIT RANGE/PER-
FORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-113, DTC P0336 CRANKSHAFT POSITION SENSOR
“A” CIRCUIT RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK CONDITION OF CRANKSHAFT PO-
SITION SENSOR.
Turn the ignition switch to OFF.
Is the crankshaft position sen-
sor installation bolt tightened
securely?
Go to step 2. Tighten the crank-
shaft position sen-
sor installation bolt
securely. <Ref. to
FU(w/o STI)-98,
Crankshaft Posi-
tion Sensor.>
2 CHECK CRANKSHAFT POSITION SENSOR
PLATE.
Is there crack or damage in the
crankshaft position sensor
plate teeth?
Replace the crank-
shaft position sen-
sor plate. <Ref. to
ME(w/o STI)-260,
Cylinder Block.>
Go to step 3.
3 CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Turn the crankshaft, and align alignment mark
on crank sprocket with alignment mark on cylin-
der block.
ST 18252AA000 CRANKSHAFT
SOCKET
Is the timing chain dislocated
from its proper position?
Correct the instal-
lation condition of
timing chain. <Ref.
to ME(w/o STI)-
116, Timing Chain
Assembly.>
Replace the crank-
shaft position sen-
sor. <Ref. to FU(w/
o STI)-98, Crank-
shaft Position Sen-
sor.>
15WRX_STI_US_EN.book 238 ージ 20  
EN(w/o STI)(diag)-239
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CI: DTC P0340 CAMSHAFT POSITION SENSOR “A” CIRCUIT (BANK 1 OR SIN-
GLE SENSOR)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-115, DTC P0340 CAMSHAFT POSITION SENSOR “A”
CIRCUIT (BANK 1 OR SINGLE SENSOR), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
4
E3
B22
EN-10806
B550
215
11
B220
01
E36
E35
213
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
3
E158
20
E35
1
2
3
21
E36
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
34
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BLACK)
INTAKE CAMSHAFT
POSITION SENSOR RH
INTAKE CAMSHAFT
POSITION SENSOR LH
MAIN RELAY
BATTERY
FUSE HOLDER
15WRX_STI_US_EN.book 239 ージ 20  
EN(w/o STI)(diag)-240
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK POWER SUPPLY OF CAMSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from camshaft
position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between camshaft
position sensor connector and engine ground.
Connector & terminal
(E36) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit or
short circuit to
ground in harness
between main re-
lay connector and
camshaft position
sensor connector
Poor contact of
coupling connector
2 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and camshaft position sensor connector.
Connector & terminal
(E158) No. 20 — (E36) No. 2:
(E158) No. 34 — (E36) No. 3:
Is the resistance less than 1 Ω? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and camshaft posi-
tion sensor con-
nector
Poor contact of
coupling connector
3 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
Measure the resistance between camshaft
position sensor connector and engine ground.
Connector & terminal
(E36) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair short cir-
cuit to ground in
harness between
ECM connector
and camshaft posi-
tion sensor con-
nector.
4 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
Measure the voltage between camshaft posi-
tion sensor connector and engine ground.
Connector & terminal
(E36) No. 2 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and cam-
shaft position
sensor connector.
Go to step 5.
5 CHECK CONDITION OF CAMSHAFT POSI-
TION SENSOR.
Is the camshaft position sensor
installation bolt tightened
securely?
Go to step 6. Tighten the cam-
shaft position sen-
sor installation bolt
securely. <Ref. to
FU(w/o STI)-104,
INSTALLATION,
Camshaft Position
Sensor.>
6 CHECK CAMSHAFT POSITION SENSOR.
Check the waveform of the camshaft position
sensor. <Ref. to EN(w/o STI)(diag)-20, Engine
Control Module (ECM) I/O Signal.>
Is there any abnormality in
waveform?
Replace the cam-
shaft position sen-
sor. <Ref. to FU(w/
o STI)-103, Cam-
shaft Position Sen-
sor.>
Repair the follow-
ing item.
Poor contact of
ECM connector
Poor contact of
camshaft position
sensor connector
Poor contact of
coupling connector
15WRX_STI_US_EN.book 240 ージ 20  
EN(w/o STI)(diag)-241
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CJ:DTC P0341 CAMSHAFT POSITION SENSOR "A" CIRCUIT RANGE/PERFOR-
MANCE (BANK 1 OR SINGLE SENSOR)
NOTE:
For the diagnostic procedure, refer to DTC P0340. <Ref. to EN(w/o STI)(diag)-239, DTC P0340 CAMSHAFT
POSITION SENSOR “A” CIRCUIT (BANK 1 OR SINGLE SENSOR), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
15WRX_STI_US_EN.book 241 ージ 20  
EN(w/o STI)(diag)-242
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CK:DTC P0345 CAMSHAFT POSITION SENSOR “A” CIRCUIT (BANK 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-118, DTC P0345 CAMSHAFT POSITION SENSOR “A”
CIRCUIT (BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
4
E3
B22
EN-10806
B550
215
11
B220
01
E36
E35
213
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
3
E158
20
E35
1
2
3
21
E36
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
34
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BLACK)
INTAKE CAMSHAFT
POSITION SENSOR RH
INTAKE CAMSHAFT
POSITION SENSOR LH
MAIN RELAY
BATTERY
FUSE HOLDER
15WRX_STI_US_EN.book 242 ージ 20  
EN(w/o STI)(diag)-243
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK POWER SUPPLY OF CAMSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from camshaft
position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between camshaft
position sensor connector and engine ground.
Connector & terminal
(E35) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit or
short circuit to
ground in harness
between main re-
lay connector and
camshaft position
sensor connector
Poor contact of
coupling connector
2 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and camshaft position sensor connector.
Connector & terminal
(E158) No. 21 — (E35) No. 2:
(E158) No. 34 — (E35) No. 3:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit in the har-
ness between the
ECM connector
and camshaft posi-
tion sensor con-
nector.
3 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
Measure the resistance between camshaft
position sensor connector and engine ground.
Connector & terminal
(E35) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair short cir-
cuit to ground in
harness between
ECM connector
and camshaft posi-
tion sensor con-
nector.
4 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
Measure the voltage between camshaft posi-
tion sensor connector and engine ground.
Connector & terminal
(E35) No. 2 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and cam-
shaft position
sensor connector.
Go to step 5.
5 CHECK CONDITION OF CAMSHAFT POSI-
TION SENSOR.
Is the camshaft position sensor
installation bolt tightened
securely?
Go to step 6. Tighten the cam-
shaft position sen-
sor installation bolt
securely. <Ref. to
FU(w/o STI)-104,
INSTALLATION,
Camshaft Position
Sensor.>
6 CHECK CAMSHAFT POSITION SENSOR.
Check the waveform of the camshaft position
sensor. <Ref. to EN(w/o STI)(diag)-20, Engine
Control Module (ECM) I/O Signal.>
Is there any abnormality in
waveform?
Replace the cam-
shaft position sen-
sor. <Ref. to FU(w/
o STI)-103, Cam-
shaft Position Sen-
sor.>
Repair the follow-
ing item.
Poor contact of
ECM connector
Poor contact of
camshaft position
sensor connector
Poor contact of
coupling connector
15WRX_STI_US_EN.book 243 ージ 20  
EN(w/o STI)(diag)-244
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CL:DTC P0346 CAMSHAFT POSITION SENSOR "A" CIRCUIT RANGE/PERFOR-
MANCE (BANK 2)
NOTE:
For the diagnostic procedure, refer to DTC P0345. <Ref. to EN(w/o STI)(diag)-242, DTC P0345 CAMSHAFT
POSITION SENSOR “A” CIRCUIT (BANK 2), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
15WRX_STI_US_EN.book 244 ージ 20  
EN(w/o STI)(diag)-245
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CM:DTC P0351 IGNITION COIL A PRIMARY/SECONDARY CIRCUIT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-119, DTC P0351 IGNITION COIL A PRIMARY/SEC-
ONDARY CIRCUIT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
ECM
3
12
E34
E32
E33
E31
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
6
B220
7
B550
216
E3B22
2
3
2
1
E31
E159
8
16
24
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10793
3
2
1
E32
3
2
1
E33
3
2
1
E34
32
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
IGNITION COIL No. 4
IGNITION COIL No. 3
IGNITION COIL No. 2
IGNITION COIL No. 1
BATTERY
FUSE HOLDER
IG RELAY
(GRAY)
15WRX_STI_US_EN.book 245 ージ 20  
EN(w/o STI)(diag)-246
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK IGNITION COIL POWER SUPPLY
CIRCUIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ignition coil.
3) Turn the ignition switch to ON.
4) Measure the voltage between ignition coil
connector and engine ground.
Connector & terminal
DTC P0351; (E31) No. 1 (+) — Engine
ground (–):
DTC P0352; (E32) No. 1 (+) — Engine
ground (–):
DTC P0353; (E33) No. 1 (+) — Engine
ground (–):
DTC P0354; (E34) No. 1 (+) — Engine
ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit or
short circuit to
ground in harness
of power supply
circuit
Blown out of fuse
Poor contact of
IG relay connector
Poor contact of
coupling connector
Faulty IG relay
2 CHECK HARNESS OF IGNITION COIL
GROUND CIRCUIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between
ignition coil connector and engine ground.
Connector & terminal
DTC P0351; (E31) No. 3 — Engine ground:
DTC P0352; (E32) No. 3 — Engine ground:
DTC P0353; (E33) No. 3 — Engine ground:
DTC P0354; (E34) No. 3 — Engine ground:
Is the resistance less than 5 Ω? Go to step 3. Repair the open
circuit in harness
between ignition
coil connector and
engine grounding
terminal.
3 CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance between ignition
coil connector and engine ground.
Connector & terminal
DTC P0351; (E31) No. 2 — Engine ground:
DTC P0352; (E32) No. 2 — Engine ground:
DTC P0353; (E33) No. 2 — Engine ground:
DTC P0354; (E34) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair the ground
short circuit of har-
ness between
ECM connector
and ignition coil
connector.
4 CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL CONNECTOR.
Measure the resistance of harness between
ECM connector and ignition coil connector.
Connector & terminal
DTC P0351; (E159) No. 8 — (E31) No. 2:
DTC P0352; (E159) No. 16 — (E32) No. 2:
DTC P0353; (E159) No. 24 — (E33) No. 2:
DTC P0354; (E159) No. 32 — (E34) No. 2:
Is the resistance less than 1 Ω? Go to step 5. Repair the open
circuit in harness
between ECM con-
nector and ignition
coil connector.
5 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Go to step 6.
6 CHECK SPARK PLUG CONDITION.
1) Remove the spark plug of the correspond-
ing cylinder. <Ref. to IG(w/o STI)-4, REMOVAL,
Spark Plug.>
2) Check the spark plug condition. <Ref. to
IG(w/o STI)-8, INSPECTION, Spark Plug.>
Is the spark plug condition nor-
mal?
Replace the igni-
tion coil. <Ref. to
IG(w/o STI)-11,
Ignition Coil.>
Replace the spark
plug. <Ref. to IG(w/
o STI)-4, Spark
Plug.>
15WRX_STI_US_EN.book 246 ージ 20  
EN(w/o STI)(diag)-247
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CN:DTC P0352 IGNITION COIL B PRIMARY/SECONDARY CIRCUIT
NOTE:
For the diagnostic procedure, refer to DTC P0351. <Ref. to EN(w/o STI)(diag)-245, DTC P0351 IGNITION
COIL A PRIMARY/SECONDARY CIRCUIT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
CO:DTC P0353 IGNITION COIL C PRIMARY/SECONDARY CIRCUIT
NOTE:
For the diagnostic procedure, refer to DTC P0351. <Ref. to EN(w/o STI)(diag)-245, DTC P0351 IGNITION
COIL A PRIMARY/SECONDARY CIRCUIT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
CP:DTC P0354 IGNITION COIL D PRIMARY/SECONDARY CIRCUIT
NOTE:
For the diagnostic procedure, refer to DTC P0351. <Ref. to EN(w/o STI)(diag)-245, DTC P0351 IGNITION
COIL A PRIMARY/SECONDARY CIRCUIT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
15WRX_STI_US_EN.book 247 ージ 20  
EN(w/o STI)(diag)-248
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CQ:DTC P0365 CAMSHAFT POSITION SENSOR “B” CIRCUIT (BANK 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-120, DTC P0365 CAMSHAFT POSITION SENSOR “B”
CIRCUIT (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK POWER SUPPLY OF CAMSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from camshaft
position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between camshaft
position sensor connector and engine ground.
Connector & terminal
(E62) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
main relay and
camshaft position
sensor connector
Poor contact of
coupling connector
4
E3
B22
EN-10807
B550
215
11
B220
01
E65
E62
213
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
3
E158
32
E65
1
2
3
33
E62
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
34
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
ECM
(BLACK)
EXHAUST CAMSHAFT
POSITION SENSOR RH
EXHAUST CAMSHAFT
POSITION SENSOR LH
MAIN RELAY
BATTERY
FUSE HOLDER
15WRX_STI_US_EN.book 248 ージ 20  
EN(w/o STI)(diag)-249
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CR:DTC P0366 CAMSHAFT POSITION SENSOR B CIRCUIT RANGE/PERFOR-
MANCE (BANK 1)
NOTE:
For the diagnostic procedure, refer to DTC P0365. <Ref. to EN(w/o STI)(diag)-248, DTC P0365 CAMSHAFT
POSITION SENSOR “B” CIRCUIT (BANK 1), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
2 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and camshaft position sensor connector.
Connector & terminal
(E158) No. 32 — (E62) No. 2:
(E158) No. 34 — (E62) No. 3:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit in the har-
ness between the
ECM connector
and camshaft posi-
tion sensor con-
nector.
3 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
Measure the resistance between camshaft
position sensor connector and engine ground.
Connector & terminal
(E62) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair short cir-
cuit to ground in
harness between
ECM connector
and camshaft posi-
tion sensor con-
nector.
4 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
Measure the voltage between camshaft posi-
tion sensor connector and engine ground.
Connector & terminal
(E62) No. 2 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and cam-
shaft position
sensor connector.
Go to step 5.
5 CHECK CONDITION OF CAMSHAFT POSI-
TION SENSOR.
Is the camshaft position sensor
installation bolt tightened
securely?
Go to step 6. Tighten the cam-
shaft position sen-
sor installation bolt
securely. <Ref. to
FU(w/o STI)-104,
INSTALLATION,
Camshaft Position
Sensor.>
6 CHECK CAMSHAFT POSITION SENSOR.
Check the waveform of the camshaft position
sensor. <Ref. to EN(w/o STI)(diag)-20, Engine
Control Module (ECM) I/O Signal.>
Is there any abnormality in
waveform?
Replace the cam-
shaft position sen-
sor. <Ref. to FU(w/
o STI)-103, Cam-
shaft Position Sen-
sor.>
Repair the follow-
ing item.
Poor contact of
ECM connector
Poor contact of
camshaft position
sensor connector
Poor contact of
coupling connector
Step Check Yes No
15WRX_STI_US_EN.book 249 ージ 20  
EN(w/o STI)(diag)-250
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CS:DTC P0390 CAMSHAFT POSITION SENSOR “B” CIRCUIT (BANK 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-122, DTC P0390 CAMSHAFT POSITION SENSOR “B”
CIRCUIT (BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
4
E3
B22
EN-10807
B550
215
11
B220
01
E65
E62
213
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
3
E158
32
E65
1
2
3
33
E62
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
34
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
ECM
(BLACK)
EXHAUST CAMSHAFT
POSITION SENSOR RH
EXHAUST CAMSHAFT
POSITION SENSOR LH
MAIN RELAY
BATTERY
FUSE HOLDER
15WRX_STI_US_EN.book 250 ージ 20  
EN(w/o STI)(diag)-251
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK POWER SUPPLY OF CAMSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from camshaft
position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between camshaft
position sensor connector and engine ground.
Connector & terminal
(E65) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit or
short circuit to
ground in harness
between main re-
lay connector and
camshaft position
sensor connector
Poor contact of
coupling connector
2 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and camshaft position sensor connector.
Connector & terminal
(E158) No. 33 — (E65) No. 2:
(E158) No. 34 — (E65) No. 3:
Is the resistance less than 1 Ω? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and camshaft posi-
tion sensor con-
nector
Poor contact of
coupling connector
3 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
Measure the resistance between camshaft
position sensor connector and engine ground.
Connector & terminal
(E65) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair short cir-
cuit to ground in
harness between
ECM connector
and camshaft posi-
tion sensor con-
nector.
4 CHECK HARNESS BETWEEN ECM AND
CAMSHAFT POSITION SENSOR CONNEC-
TOR.
Measure the voltage between camshaft posi-
tion sensor connector and engine ground.
Connector & terminal
(E65) No. 2 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and cam-
shaft position
sensor connector.
Go to step 5.
5 CHECK CONDITION OF CAMSHAFT POSI-
TION SENSOR.
Is the camshaft position sensor
installation bolt tightened
securely?
Go to step 6. Tighten the cam-
shaft position sen-
sor installation bolt
securely. <Ref. to
FU(w/o STI)-104,
INSTALLATION,
Camshaft Position
Sensor.>
6 CHECK CAMSHAFT POSITION SENSOR.
Check the waveform of the camshaft position
sensor. <Ref. to EN(w/o STI)(diag)-20, Engine
Control Module (ECM) I/O Signal.>
Is there any abnormality in
waveform?
Replace the cam-
shaft position sen-
sor. <Ref. to FU(w/
o STI)-103, Cam-
shaft Position Sen-
sor.>
Repair the follow-
ing item.
Poor contact of
ECM connector
Poor contact of
camshaft position
sensor connector
Poor contact of
coupling connector
15WRX_STI_US_EN.book 251 ージ 20  
EN(w/o STI)(diag)-252
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CT:DTC P0391 CAMSHAFT POSITION SENSOR B CIRCUIT RANGE/PERFOR-
MANCE (BANK 2)
NOTE:
For the diagnostic procedure, refer to DTC P0390. <Ref. to EN(w/o STI)(diag)-250, DTC P0390 CAMSHAFT
POSITION SENSOR “B” CIRCUIT (BANK 2), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
15WRX_STI_US_EN.book 252 ージ 20  
EN(w/o STI)(diag)-253
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CU:DTC P0400 EXHAUST GAS RECIRCULATION FLOW
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-123, DTC P0400 EXHAUST GAS RECIRCULATION
FLOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Movement performance problem when engine is low speed.
Improper idling
Movement performance problem
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «Mani. Absolute Pres-
sure» using the Subaru Select Monitor or a gen-
eral scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Mani. Absolute
Pressure» 53.3 kPa (400
mmHg, 15.75 inHg) or more?
Make sure that the
EGR control valve,
manifold absolute
pressure sensor
and throttle body
are installed
securely.
Go to step 2.
2 CHECK EGR CONTROL VALVE.
Remove the EGR control valve.
Are there any holes, clogged
lines or foreign matters in the
EGR system?
Repair the EGR
system.
Replace EGR con-
trol valve. <Ref. to
EC(w/o STI)-35,
EGR Control
Valve.>
15WRX_STI_US_EN.book 253 ージ 20  
EN(w/o STI)(diag)-254
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CV:DTC P0420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD (BANK 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-126, DTC P0420 CATALYST SYSTEM EFFICIENCY
BELOW THRESHOLD (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Idle mixture is out of specifications.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 254 ージ 20  
EN(w/o STI)(diag)-255
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK EXHAUST SYSTEM.
Check for gas leaks or air suction caused by
loose or dislocated nuts and bolts, and open
hole at exhaust pipes.
NOTE:
Check the following positions.
Between cylinder head and front exhaust
pipe
Between front exhaust pipe and front catalytic
converter
Between front catalytic converter and rear
catalytic converter
Loose or improperly attached front oxygen
(A/F) sensor or rear oxygen sensor
Is there any fault in exhaust
system?
Repair or replace
the exhaust sys-
tem. <Ref. to
EX(w/o STI)-2,
General Descrip-
tion.>
Go to step 2.
2 CHECK WAVEFORM DATA ON THE SUBA-
RU SELECT MONITOR (WHILE DRIVING).
1) Drive at a constant speed between 80 —
112 km/h (50 — 70 MPH).
2) After 5 minutes have elapsed in the condi-
tion of step 1), use the Subaru Select Monitor
while still driving to read the waveform data.
At normal condition
At abnormal condition (numerous inversion)
Is a normal waveform dis-
played?
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
Go to step 3.
EN-06666
1
0
1.5
0.5
10 sec/div
REAR OXYGEN
SENSOR VOLTAGE
(V)
A/F SENSOR
OUTPUT LAMBDA 1
EN-06667
1
0
1.5
0.5
10 sec/div
REAR OXYGEN
SENSOR VOLTAGE
(V)
A/F SENSOR
OUTPUT LAMBDA 1
15WRX_STI_US_EN.book 255 ージ 20  
EN(w/o STI)(diag)-256
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
3 CHECK WAVEFORM DATA ON THE SUBA-
RU SELECT MONITOR (WHILE IDLING).
1) Run the engine at idle.
2) In the condition of step 1), use the Subaru
Select Monitor to read the waveform data.
At normal condition
At abnormal condition 1 (numerous inversion)
At abnormal condition 2 (noise input)
Is a normal waveform dis-
played?
Go to step 4. The waveform is
displayed at abnor-
mal condition 1: Go
to step 4.
The waveform is
displayed at abnor-
mal condition 2: Go
to step 5.
4 CHECK CATALYTIC CONVERTER. Is the catalytic converter dam-
aged?
Replace the cata-
lytic converter.
<Ref. to EX(w/o
STI)-35, Center
Exhaust Pipe.>
Go to step 5.
5 CHECK REAR OXYGEN SENSOR CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 6.
Step Check Yes No
EN-06668
1
0
10 sec/div
REAR OXYGEN
SENSOR VOLTAGE
(V)
EN-06669
1
0
10 sec/div
REAR OXYGEN
SENSOR VOLTAGE
(V)
EN-06670
1
0
10 sec/div
REAR OXYGEN
SENSOR VOLTAGE
(V)
15WRX_STI_US_EN.book 256 ージ 20  
EN(w/o STI)(diag)-257
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 42 — (E25) No. 3:
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 7. Repair the open
circuit of harness
between ECM con-
nector and rear
oxygen sensor
connector.
7 CHECK REAR OXYGEN SENSOR SHIELD.
1) Turn the ignition switch to OFF.
2) Expose the rear oxygen sensor connector
body side harness sensor shield.
3) Measure the resistance between sensor
shield and engine ground.
Is the resistance less than 1 Ω? Go to step 8. Repair the open
circuit of rear oxy-
gen sensor har-
ness.
8 CHECK ENGINE OIL AMOUNT AND EX-
HAUST GAS.
1) Check the engine oil amount. <Ref. to LU(w/
o STI)-10, INSPECTION, Engine Oil.>
2) Check exhaust gas during idling.
Does the engine oil amount
drop or white smoke emit from
the muffler?
Check the engine,
and repair the
defective part.
<Ref. to ME(w/o
STI)-352,
INSPECTION,
Engine Trouble in
General.>
After repairing the
engine, replace the
front catalytic con-
verter. <Ref. to
EX(w/o STI)-35,
Center Exhaust
Pipe.>
After the catalytic
converter is
replaced, perform
step 2 to check the
normal waveform
is displayed, and
then exit the proce-
dure.
Go to step 9.
9 CHECK IGNITION SYSTEM.
1) Check the spark plug. <Ref. to IG(w/o STI)-
8, INSPECTION, Spark Plug.>
2) Check the status of the ignition coil connec-
tor and the spark plug terminal.
Is there any fault in the ignition
system?
After repairing the
ignition system,
replace the front
catalytic con-
verter. <Ref. to
EX(w/o STI)-35,
Center Exhaust
Pipe.>
After the catalytic
converter is
replaced, perform
step 2 to check the
normal waveform
is displayed, and
then exit the proce-
dure.
Go to step 10.
Step Check Yes No
15WRX_STI_US_EN.book 257 ージ 20  
EN(w/o STI)(diag)-258
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
10 CHECK FUEL SYSTEM.
1) Refer to and check the items in “Insufficient
fuel supply to fuel injector” (except for “a. Fuel
pump does not operate.”) and “Leakage or blow
out of fuel”. <Ref. to FU(w/o STI)-202, INSPEC-
TION, Fuel System Trouble in General.>
2) Check throttle body. <Ref. to FU(w/o STI)-
16, INSPECTION, Throttle Body.>
3) Check intake manifold. <Ref. to FU(w/o
STI)-42, INSPECTION, Intake Manifold.>
Is there any fault in the fuel sys-
tem?
After repairing the
fuel system,
replace the front
catalytic con-
verter. <Ref. to
EX(w/o STI)-35,
Center Exhaust
Pipe.>
After the catalytic
converter is
replaced, perform
step 2 to check the
normal waveform
is displayed, and
then exit the proce-
dure.
Go to step 11.
11 CHECK DTC. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
After checking the
DTC, replace the
front catalytic con-
verter. <Ref. to
EX(w/o STI)-35,
Center Exhaust
Pipe.>
After the catalytic
converter is
replaced, perform
step 2 to check the
normal waveform
is displayed, and
then exit the proce-
dure.
Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 258 ージ 20  
EN(w/o STI)(diag)-259
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CW:DTC P0441 EVAPORATIVE EMISSION CONT. SYS. INCORRECT PURGE
FLOW
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-128, DTC P0441 EVAPORATIVE EMISSION CONT.
SYS. INCORRECT PURGE FLOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK PURGE CONTROL SOLENOID
VALVE.
Operate the purge control solenoid valve using
the Subaru Select Monitor.
NOTE:
For detailed procedures, refer to “System Oper-
ation Check Mode”. <Ref. to EN(w/o STI)(diag)-
62, System Operation Check Mode.>
Does the purge control sole-
noid valve operate?
Go to step 3. Replace the purge
control solenoid
valve. <Ref. to
EC(w/o STI)-22,
Purge Control
Solenoid Valve.>
3 CHECK EVAPORATIVE EMISSION CON-
TROL SYSTEM LINE.
Turn the ignition switch to OFF.
Are there holes, cracks, clog-
ging, or disconnection, miscon-
nection of hoses or pipes in
evaporative emission control
system?
Repair or replace
the hoses or pipes.
Repair the poor
contact of ECM
connector.
15WRX_STI_US_EN.book 259 ージ 20  
EN(w/o STI)(diag)-260
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CX:DTC P0451 EVAPORATIVE EMISSION SYSTEM PRESSURE SENSOR/
SWITCH RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-130, DTC P0451 EVAPORATIVE EMISSION SYSTEM
PRESSURE SENSOR/SWITCH RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Cri-
teria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK CURRENT DATA.
1) Turn the ignition switch to ON (engine OFF).
2) Using the Subaru Select Monitor or general
scan tool, read the value in «Absolute Evap
Sys. Pressure» and «Mani. Absolute Pres-
sure», and compare them with the actual atmo-
spheric pressure.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
To read the actual atmospheric pressure,
connect the Subaru Select Monitor or general
scan tool to the other known good vehicle.
Is the difference with the actual
atmospheric pressure 6.2 kPa
(46.5 mmHg, 1.83 inHg) or
more?
Replace the part
that showed larger
deviation from the
actual atmospheric
pressure than the
other.
If deviations in
value for «Absolute
Evap Sys. Pres-
sure» is larger:
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
If deviations in
value for «Mani.
Absolute Pres-
sure» is larger:
Replace the mani-
fold absolute pres-
sure and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-120, Mani-
fold Absolute Pres-
sure and Intake Air
Temperature Sen-
sor.>
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
15WRX_STI_US_EN.book 260 ージ 20  
EN(w/o STI)(diag)-261
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CY:DTC P0452 EVAPORATIVE EMISSION SYSTEM PRESSURE SENSOR/
SWITCH LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-132, DTC P0452 EVAPORATIVE EMISSION SYSTEM
PRESSURE SENSOR/SWITCH LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B97
1234 56789
10 11 12 13 14 15 16 17 18 19 20
78
5
6
34
2
1
B122
EN-10808
20
15
16
18
R1B97
19
17
*
*
B122
J/C
*
3
4
R400
1234
5678
R400
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
3
B134
5
1
6
7
8
19
27
18
15
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BROWN)
VACUUM
PUMP
MAIN RELAY
BATTERY
FUSE HOLDER
LEAK CHECK VALVE ASSY
SWITCHING
VALVE
PRESSURE
SENSOR
: TERMINAL No. OPTIONAL ARRANGEMENT
15WRX_STI_US_EN.book 261 ージ 20  
EN(w/o STI)(diag)-262
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Turn the ignition switch to ON.
2) Read the value of «Absolute Evap Sys.
Pressure» using the Subaru Select Monitor or a
general scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value in «Absolute Evap
Sys. Pressure» 34 kPa (255
mmHg, 10 inHg) or less?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK POWER SUPPLY OF LEAK CHECK
VALVE ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the leak
check valve assembly.
3) Turn the ignition switch to ON.
4) Measure the voltage between the leak
check valve assembly connector and chassis
ground.
Connector & terminal
(R400) No. 6 (+) — Chassis ground (–):
Is the voltage 4.5 V or more? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and the leak check
valve assembly
connector
Poor contact of
ECM connector
Poor contact of
coupling connector
3 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and chassis ground.
Connector & terminal
(B134) No. 15 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair the short
circuit to ground in
harness between
ECM connector
and leak check
valve assembly
connector.
4 CHECK FOR POOR CONTACT.
Check for poor contact of leak check valve
assembly connector.
Is there poor contact in the leak
check valve assembly connec-
tor?
Repair the poor
contact in the leak
check valve
assembly connec-
tor.
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
15WRX_STI_US_EN.book 262 ージ 20  
EN(w/o STI)(diag)-263
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CZ:DTC P0453 EVAPORATIVE EMISSION SYSTEM PRESSURE SENSOR/
SWITCH HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-133, DTC P0453 EVAPORATIVE EMISSION SYSTEM
PRESSURE SENSOR/SWITCH HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B97
1234 56789
10 11 12 13 14 15 16 17 18 19 20
78
5
6
34
2
1
B122
EN-10808
20
15
16
18
R1B97
19
17
*
*
B122
J/C
*
3
4
R400
1234
5678
R400
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
3
B134
5
1
6
7
8
19
27
18
15
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BROWN)
VACUUM
PUMP
MAIN RELAY
BATTERY
FUSE HOLDER
LEAK CHECK VALVE ASSY
SWITCHING
VALVE
PRESSURE
SENSOR
: TERMINAL No. OPTIONAL ARRANGEMENT
15WRX_STI_US_EN.book 263 ージ 20  
EN(w/o STI)(diag)-264
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Turn the ignition switch to ON.
2) Read the value of «Absolute Evap Sys.
Pressure» using the Subaru Select Monitor or a
general scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value in «Absolute Evap
Sys. Pressure» 125 kPa (938
mmHg, 36.9 inHg) or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the leak check valve assembly.
3) Measure the resistance of harness between
ECM connector and the leak check valve
assembly connector.
Connector & terminal
(B134) No. 15 — (R400) No. 7:
(B134) No. 19 — (R400) No. 8:
Is the resistance less than 1 Ω? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and the leak check
valve assembly
connector
Poor contact of
coupling connector
Poor contact of
joint connector
3 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and the leak
check valve assembly connector.
Is there poor contact in ECM
and the leak check valve
assembly connector?
Repair the poor
contact of ECM
and the leak check
valve assembly
connector.
Go to step 4.
4 CHECK LEAK CHECK VALVE ASSEMBLY.
Check the pressure sensor of the leak check
valve assembly. <Ref. to EC(w/o STI)-70,
CHECK PRESSURE SENSOR, INSPECTION,
Leak Check Valve Assembly.>
Is the pressure sensor of the
leak check valve assembly OK?
Repair the short
circuit to power in
harness between
ECM connector
and leak check
valve assembly
connector.
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
15WRX_STI_US_EN.book 264 ージ 20  
EN(w/o STI)(diag)-265
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DA:DTC P0455 EVAPORATIVE EMISSION SYSTEM LEAK DETECTED (LARGE
LEAK)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-134, DTC P0455 EVAPORATIVE EMISSION SYSTEM
LEAK DETECTED (LARGE LEAK), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Fuel odor
There is a hole of more than 1.0 mm (0.04 in) dia. in evaporation system or fuel tank.
Fuel filler cap loose or lost
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FUEL FILLER CAP.
1) Turn the ignition switch to OFF.
2) Check the fuel filler cap.
NOTE:
The DTC is stored in memory if fuel filler cap is
or was loose or if the cap chain has caught while
tightening.
Is the fuel filler cap tightened
securely?
Go to step 2. Tighten fuel filler
cap securely.
2 CHECK FUEL FILLER CAP. Is the fuel filler cap genuine? Go to step 3. Replace with a
genuine fuel filler
cap.
3 CHECK FUEL FILLER PIPE GASKET. Is there any damage to the seal
between fuel filler cap and fuel
filler pipe?
Repair or replace
the fuel filler cap
and fuel filler pipe.
<Ref. to FU(w/o
STI)-163, Fuel
Filler Pipe.>
Go to step 4.
4 CHECK PURGE CONTROL SOLENOID
VALVE.
Check air-tightness of the purge control sole-
noid valve. <Ref. to EC(w/o STI)-29, INSPEC-
TION, Purge Control Solenoid Valve.>
Is the purge control solenoid
valve OK?
Go to step 5. Replace the purge
control solenoid
valve. <Ref. to
EC(w/o STI)-22,
Purge Control
Solenoid Valve.>
5 CHECK EVAPORATIVE EMISSION CON-
TROL SYSTEM LINE.
Are there holes on the evapora-
tion line?
Repair or replace
the evaporation
line. <Ref. to FU(w/
o STI)-194, Fuel
Delivery and Evap-
oration Lines.>
Go to step 6.
6 CHECK CANISTER. Are there holes on the canis-
ter?
Replace the canis-
ter. <Ref. to EC(w/
o STI)-8, Canis-
ter.>
Go to step 7.
7 CHECK LEAK CHECK VALVE ASSEMBLY. Are there damage or holes on
the leak check valve assembly?
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
Go to step 8.
8 CHECK FUEL TANK.
Remove the fuel tank. <Ref. to FU(w/o STI)-
152, Fuel Tank.>
Are there damage or holes on
the fuel tank?
Repair or replace
the fuel tank. <Ref.
to FU(w/o STI)-
152, Fuel Tank.>
Go to step 9.
15WRX_STI_US_EN.book 265 ージ 20  
EN(w/o STI)(diag)-266
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DB:DTC P0456 EVAPORATIVE EMISSION CONTROL SYSTEM LEAK DETECT-
ED (VERY SMALL LEAK)
NOTE:
For the diagnostic procedure, refer to DTC P0455. <Ref. to EN(w/o STI)(diag)-265, DTC P0455 EVAPORA-
TIVE EMISSION SYSTEM LEAK DETECTED (LARGE LEAK), Diagnostic Procedure with Diagnostic Trou-
ble Code (DTC).>
9 CHECK ANY OTHER MECHANICAL TROU-
BLE IN EVAPORATIVE EMISSION CON-
TROL SYSTEM.
Are there holes, cracks, clog-
ging, or disconnection, miscon-
nection of hoses or pipes in
evaporative emission control
system?
Repair or replace
the hoses or pipes.
Repair the poor
contact of ECM
connector.
Step Check Yes No
15WRX_STI_US_EN.book 266 ージ 20  
EN(w/o STI)(diag)-267
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DC:DTC P0458 EVAPORATIVE EMISSION SYSTEM PURGE CONTROL VALVE
CIRCUIT LOW
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-140, DTC P0458 EVAPORATIVE EMISSION SYSTEM
PURGE CONTROL VALVE CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 4 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Go to step 3.
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
12
E52
4
E3
B22
EN-10809
B550
215
11
B220
01
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
E159
4
E52
1
212
E4
B22
12
3
4
5678
9
10 11 12
1413 15 16
12
E4
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
PURGE CONTROL
SOLENOID VALVE 1
PURGE CONTROL
SOLENOID VALVE 2
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 267 ージ 20  
EN(w/o STI)(diag)-268
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
3 CHECK POWER SUPPLY TO PURGE CON-
TROL SOLENOID VALVE 1 CONNECTOR.
Measure the voltage between purge control
solenoid valve 1 connector and engine ground.
Connector & terminal
(E4) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the power
supply circuit.
4 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 1
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
purge control solenoid valve 1.
3) Measure the resistance between the purge
control solenoid valve 1 connector and engine
ground.
Connector & terminal
(E4) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the ground
short circuit of har-
ness between
ECM connector
and purge control
solenoid valve 1
connector.
5 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 1
CONNECTOR.
Measure the resistance of harness between
ECM connector and purge control solenoid
valve 1 connector.
Connector & terminal
(E159) No. 4 — (E4) No. 2:
Is the resistance less than 1 Ω? Go to step 6. Repair the open
circuit in harness
between ECM con-
nector and purge
control solenoid
valve 1 connector.
6 CHECK PURGE CONTROL SOLENOID
VALVE 1.
1) Remove the purge control solenoid valve 1.
2) Measure the resistance between purge con-
trol solenoid valve 1 terminals.
Terminals
No. 1 — No. 2:
Is the resistance 10 — 100 Ω? Repair the poor
contact of the
purge control sole-
noid valve 1 con-
nector.
Replace the purge
control solenoid
valve 1. <Ref. to
EC(w/o STI)-22,
Purge Control
Solenoid Valve.>
Step Check Yes No
15WRX_STI_US_EN.book 268 ージ 20  
EN(w/o STI)(diag)-269
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DD:DTC P0459 EVAPORATIVE EMISSION SYSTEM PURGE CONTROL VALVE
CIRCUIT HIGH
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-141, DTC P0459 EVAPORATIVE EMISSION SYSTEM
PURGE CONTROL VALVE CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 1
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
purge control solenoid valve 1.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 4 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
harness between
ECM connector
and purge control
solenoid valve 1
connector.
Go to step 2.
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
12
E52
4
E3
B22
EN-10809
B550
215
11
B220
01
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
E159
4
E52
1
212
E4
B22
12
3
4
5678
9
10 11 12
1413 15 16
12
E4
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
PURGE CONTROL
SOLENOID VALVE 1
PURGE CONTROL
SOLENOID VALVE 2
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 269 ージ 20  
EN(w/o STI)(diag)-270
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK PURGE CONTROL SOLENOID
VALVE 1.
1) Turn the ignition switch to OFF.
2) Measure the resistance between purge con-
trol solenoid valve 1 terminals.
Terminals
No. 1 — No. 2:
Is the resistance less than 1 Ω? Replace the purge
control solenoid
valve 1. <Ref. to
EC(w/o STI)-22,
Purge Control
Solenoid Valve.>
Repair the poor
contact of ECM
connector.
Step Check Yes No
15WRX_STI_US_EN.book 270 ージ 20  
EN(w/o STI)(diag)-271
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DE:DTC P0461 FUEL LEVEL SENSOR “A” CIRCUIT RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-142, DTC P0461 FUEL LEVEL SENSOR “A” CIRCUIT
RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
DF:DTC P0462 FUEL LEVEL SENSOR “A” CIRCUIT LOW
NOTE:
For the diagnostic procedure, refer to DTC P0463. <Ref. to EN(w/o STI)(diag)-272, DTC P0463 FUEL LEV-
EL SENSOR “A” CIRCUIT HIGH, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Replace the fuel
level sensor and
fuel sub level sen-
sor. <Ref. to FU(w/
o STI)-173, Fuel
Level Sensor.>
<Ref. to FU(w/o
STI)-176, Fuel Sub
Level Sensor.>
15WRX_STI_US_EN.book 271 ージ 20  
EN(w/o STI)(diag)-272
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DG:DTC P0463 FUEL LEVEL SENSOR “A” CIRCUIT HIGH
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-144, DTC P0463 FUEL LEVEL SENSOR “A” CIRCUIT
HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
DH:DTC P0500 VEHICLE SPEED SENSOR “A”
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-145, DTC P0500 VEHICLE SPEED SENSOR “A”, Diag-
nostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is DTC P0462 or P0463 dis-
played on the Subaru Select
Monitor?
Check the combi-
nation meter. <Ref.
to IDI(diag)-2,
Basic Diagnostic
Procedure.>
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
Step Check Yes No
1 CHECK DTC OF VDC.
Check DTC of VDC.
Is DTC of VDC displayed? Perform the diag-
nosis according to
DTC. <Ref. to
VDC(diag)-42, List
of Diagnostic Trou-
ble Code (DTC).>
Repair the poor
contact of ECM
connector.
15WRX_STI_US_EN.book 272 ージ 20  
EN(w/o STI)(diag)-273
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DI: DTC P0506 IDLE AIR CONTROL SYSTEM RPM LOWER THAN EXPECTED
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-146, DTC P0506 IDLE AIR CONTROL SYSTEM RPM
LOWER THAN EXPECTED, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Hard to start the engine.
Engine does not start.
Improper idling
Engine stalls.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK AIR CLEANER ELEMENT.
1) Turn the ignition switch to OFF.
2) Check the air cleaner element.
Is there excessive clogging on
air cleaner element?
Replace the air
cleaner element.
<Ref. to IN(w/o
STI)-7, Air Cleaner
Element.>
Go to step 3.
3 CHECK ELECTRONIC THROTTLE CON-
TROL.
1) Remove the electronic throttle control. <Ref.
to FU(w/o STI)-15, REMOVAL, Throttle Body.>
2) Check the electronic throttle control.
Are foreign matter found inside
electronic throttle control?
Remove foreign
matter from elec-
tronic throttle con-
trol.
Perform the diag-
nosis of DTC
P2101. <Ref. to
EN(w/o STI)(diag)-
423, DTC P2101
THROTTLE
ACTUATOR CON-
TROL MOTOR
CIRCUIT RANGE/
PERFORMANCE,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
15WRX_STI_US_EN.book 273 ージ 20  
EN(w/o STI)(diag)-274
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DJ:DTC P0507 IDLE AIR CONTROL SYSTEM RPM HIGHER THAN EXPECTED
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-147, DTC P0507 IDLE AIR CONTROL SYSTEM RPM
HIGHER THAN EXPECTED, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine keeps running at higher speed than specified idle speed.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK AIR INTAKE SYSTEM.
1) Start and idle the engine.
2) Check the following items.
Loose installation of intake manifold and
throttle body
Cracks of intake manifold gasket and throttle
body gasket
Disconnection of vacuum hoses
Is there any fault in air intake
system?
Repair air suction
and leaks.
Go to step 3.
3 CHECK ELECTRONIC THROTTLE CON-
TROL.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control. <Ref.
to FU(w/o STI)-15, REMOVAL, Throttle Body.>
3) Check the electronic throttle control.
Are foreign matter found inside
electronic throttle control?
Remove foreign
matter from elec-
tronic throttle con-
trol.
Perform the diag-
nosis of DTC
P2101. <Ref. to
EN(w/o STI)(diag)-
423, DTC P2101
THROTTLE
ACTUATOR CON-
TROL MOTOR
CIRCUIT RANGE/
PERFORMANCE,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
15WRX_STI_US_EN.book 274 ージ 20  
EN(w/o STI)(diag)-275
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DK:DTC P050A COLD START IDLE AIR CONTROL SYSTEM PERFORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-148, DTC P050A COLD START IDLE AIR CONTROL
SYSTEM PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine keeps running at higher speed than specified idle speed.
Engine keeps running at a lower speed than the specified idle speed.
Engine stalls.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 275 ージ 20  
EN(w/o STI)(diag)-276
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
2
E6
E5
E17
E16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
2
1
E5
B11
B23
B35
EN-10794
2
1
E16
2
1
E6
2
1
E17
B47
B12
B24
B36
B48
C18
C17
C10
A35
A47
16
15
E3
B22
C26
C25
B134A:
E158B:
C: E159
ECM
FUEL INJECTOR No. 4
FUEL INJECTOR No. 3
FUEL INJECTOR No. 2
FUEL INJECTOR No. 1
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 276 ージ 20  
EN(w/o STI)(diag)-277
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK ENGINE OIL. Is there a proper amount of
engine oil?
Go to step 3. Replace engine oil.
<Ref. to LU(w/o
STI)-11,
REPLACEMENT,
Engine Oil.>
3 CHECK EXHAUST SYSTEM. Are there holes or loose bolts
on exhaust system?
Repair the exhaust
system.
Go to step 4.
ECM
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B225
14
17
15
16
B550
215
317
B220
1011
E57
B17
B29
B18
B30
6
5
3
2
4
1
C1
C2
A39
A11
B225B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10800
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
BATTERY
ELECTRONIC
THROTTLE
CONTROL
MAIN RELAY
FUSE HOLDER
ELECTRONIC
THROTTLE CONTROL
RELAY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 277 ージ 20  
EN(w/o STI)(diag)-278
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
4 CHECK AIR INTAKE SYSTEM. Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
Go to step 5.
5 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 328 —
358 kPa (3.3 — 3.7 kgf/cm
2
, 48
— 52 psi)?
Go to step 6. Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
6 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm up completely.
2) Read the value of «Coolant Temp.» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Coolant Temp
75°C (167°F) or more?
Go to step 7. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
7 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Read the value of «Mass Air Flow» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Mass Air
Flow» 2.0 — 5.0 g/s (0.26 —
0.66 lb/m)?
Go to step 8. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 278 ージ 20  
EN(w/o STI)(diag)-279
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
8 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Open the front hood.
6) Measure the ambient temperature.
7) Read the value of «IAT Sensor #11» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Subtract ambient temperature
value from the value of «IAT
Sensor #11». Is the obtained
value –10 — 50°C (–18 —
90°F)?
Go to step 9. Check the mass air
flow and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-118, Mass
Air Flow and Intake
Air Temperature
Sensor.>
9 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel injector
on faulty cylinders.
3) Measure the resistance between fuel injec-
tor connector and engine ground on faulty cylin-
ders.
Connector & terminal
#1 (E5) No. 1 — Engine ground:
#1 (E5) No. 2 — Engine ground:
#2 (E16) No. 1 — Engine ground:
#2 (E16) No. 2 — Engine ground:
#3 (E6) No. 1 — Engine ground:
#3 (E6) No. 2 — Engine ground:
#4 (E17) No. 1 — Engine ground:
#4 (E17) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 10. Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
10 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance of harness between
ECM and fuel injector connector on faulty cylin-
ders.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Go to step 11. Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
11 CHECK FUEL INJECTOR.
Check the fuel injector on faulty cylinder. <Ref.
to FU(w/o STI)-70, INSPECTION, Fuel Injec-
tor.>
Are fuel injectors OK? Go to step 12. Replace the faulty
fuel injector. <Ref.
to FU(w/o STI)-51,
Fuel Injector.>
Step Check Yes No
15WRX_STI_US_EN.book 279 ージ 20  
EN(w/o STI)(diag)-280
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
12 CHECK INSTALLATION CONDITION OF
CAMSHAFT POSITION SENSOR/CRANK-
SHAFT POSITION SENSOR.
Is the camshaft position sensor
or crankshaft position sensor
loosely installed?
Tighten the cam-
shaft position sen-
sor or crankshaft
position sensor.
<Ref. to FU(w/o
STI)-104, INSTAL-
LATION, Cam-
shaft Position
Sensor.> <Ref. to
FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
Go to step 13.
13 CHECK CRANKSHAFT POSITION SENSOR
PLATE.
Is the crankshaft position sen-
sor plate rusted or does it have
broken teeth?
Replace the crank-
shaft position sen-
sor plate. <Ref. to
ME(w/o STI)-260,
Cylinder Block.>
Go to step 14.
14 CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Turn the crankshaft using ST, and align the
alignment mark on crank sprocket with align-
ment mark on cylinder block.
ST 18252AA000 CRANKSHAFT
SOCKET
Is the timing chain dislocated
from its proper position?
Correct the instal-
lation condition of
timing chain. <Ref.
to ME(w/o STI)-
116, Timing Chain
Assembly.>
Go to step 15.
15 CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to terminals No. 16 and
No. 17 of electronic throttle control relay.
4) Measure the resistance between electronic
throttle control relay terminals.
Terminals
No. 14 — No. 15:
Is the resistance less than 1 Ω? Go to step 16. Replace the elec-
tronic throttle con-
trol relay. <Ref. to
FU(w/o STI)-139,
Electronic Throttle
Control Relay.>
16 CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
Measure the voltage between electronic throttle
control relay connector and chassis ground.
Connector & terminal
(B225) No. 15 (+) — Chassis ground (–):
Is the voltage 10 V or more? Go to step 17. Repair the open or
ground short circuit
of power supply
circuit.
17 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Disconnect the connector from ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B225) No. 17 (+) — Chassis ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.
Go to step 18.
Step Check Yes No
15WRX_STI_US_EN.book 280 ージ 20  
EN(w/o STI)(diag)-281
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
18 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B225) No. 14 — Chassis ground:
(B225) No. 17 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 19. Repair the short
circuit to ground in
harness between
ECM connector
and electronic
throttle control
relay connector.
19 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
Measure the resistance between ECM connec-
tor and electronic throttle control relay connec-
tor.
Connector & terminal
(B134) No. 39 — (B225) No. 17:
(B134) No. 11 — (B225) No. 14:
Is the resistance less than 1 Ω? Go to step 20. Repair the open
circuit in harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.
20 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from electronic
throttle control.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 18 — Engine ground:
(E158) No. 17 — Engine ground:
(E158) No. 29 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 21. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
21 CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 1 — Engine ground:
(E57) No. 4 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 22. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
Replace the ECM if
defective. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
22 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness between
ECM connector and electronic throttle control
connector.
Connector & terminal
(E158) No. 17 — (E57) No. 1:
(E158) No. 30 — (E57) No. 3:
(E158) No. 29 — (E57) No. 4:
Is the resistance less than 1 Ω? Go to step 23. Repair the open
circuit of harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Step Check Yes No
15WRX_STI_US_EN.book 281 ージ 20  
EN(w/o STI)(diag)-282
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
23 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 3 — Engine ground:
Is the resistance less than 5 Ω? Go to step 24. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
ECM connector
Poor contact of
coupling connector
24 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 1 (+) — Engine ground (–):
(E57) No. 4 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Go to step 25.
25 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(E158) No. 18 — (E158) No. 17:
(E158) No. 18 — (E158) No. 29:
Is the resistance 1 MΩ or
more?
Go to step 26. Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
26 CHECK SENSOR OUTPUT.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Read the value of «Main-Throttle Sensor»
using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «Main-Throttle
Sensor» 0.60 — 0.65 V?
Go to step 27. Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to FU(w/o
STI)-15, Throttle
Body.>
27 CHECK SENSOR OUTPUT.
Read the value of «Sub-Throttle Sensor» using
Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «Sub-Throttle
Sensor» 0.60 — 0.65 V?
Go to step 28. Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to FU(w/o
STI)-15, Throttle
Body.>
Step Check Yes No
15WRX_STI_US_EN.book 282 ージ 20  
EN(w/o STI)(diag)-283
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
28 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance between ECM con-
nector and electronic throttle control connector.
Connector & terminal
(E159) No. 1 — (E57) No. 5:
(E159) No. 2 — (E57) No. 6:
Is the resistance less than 1 Ω? Go to step 29. Repair the open
circuit of harness
between ECM con-
nector and elec-
tronic throttle
control.
29 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 5 (+) — Engine ground (–):
(E57) No. 6 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Go to step 30.
30 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 5 — Engine ground:
(E57) No. 6 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 31. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
31 CHECK ELECTRONIC THROTTLE CON-
TROL MOTOR HARNESS.
Measure the resistance between electronic
throttle control connectors.
Connector & terminal
(E57) No. 5 — (E57) No. 6:
Is the resistance 1 MΩ or
more?
Go to step 32. Repair the short
circuit in harness
between ECM con-
nector and elec-
tronic throttle
control connector.
32 CHECK ELECTRONIC THROTTLE CON-
TROL GROUND CIRCUIT.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(B134) No. 35 — Engine ground:
(B134) No. 47 — Engine ground:
(E159) No. 10 — Engine ground:
(E159) No. 17 — Engine ground:
(E159) No. 18 — Engine ground:
(E159) No. 25 — Engine ground:
(E159) No. 26 — Engine ground:
Is the resistance less than 5 Ω? Go to step 33. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
coupling connector
33 CHECK ELECTRONIC THROTTLE CON-
TROL.
Measure the resistance between electronic
throttle control terminals.
Terminals
No. 5 — No. 6:
Is the resistance 50 Ω or less? Go to step 34. Replace the elec-
tronic throttle con-
trol. <Ref. to FU(w/
o STI)-15, Throttle
Body.>
Step Check Yes No
15WRX_STI_US_EN.book 283 ージ 20  
EN(w/o STI)(diag)-284
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DL:DTC P050B COLD START IGNITION TIMING PERFORMANCE
NOTE:
For the diagnostic procedure, refer to DTC P050A. <Ref. to EN(w/o STI)(diag)-275, DTC P050A COLD
START IDLE AIR CONTROL SYSTEM PERFORMANCE, Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
34 CHECK ELECTRONIC THROTTLE CON-
TROL.
Move the throttle valve to the fully open and fully
closed positions with fingers.
Check that the valve returns to the specified
position when releasing fingers.
Does the valve return to the
specified position? Standard
value: 3 mm (0.12 in) from fully
closed position
Repair the poor
contact of ECM
connector.
Replace the elec-
tronic throttle con-
trol. <Ref. to FU(w/
o STI)-15, Throttle
Body.>
Step Check Yes No
15WRX_STI_US_EN.book 284 ージ 20  
EN(w/o STI)(diag)-285
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DM:DTC P0512 STARTER REQUEST CIRCUIT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-150, DTC P0512 STARTER REQUEST CIRCUIT, Diag-
nostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 285 ージ 20  
EN(w/o STI)(diag)-286
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
CVT
CVT
MT
CVT
MT
CVT
B23
12345
6789
10
CVT
CVT
721
MT
11
12
B12
T3
MT
MT
B134
B14
1
M
B574C:
B572A:
3
B576B575
21
A7
C6
1
B106
3
2
B225
5
28
30
29
B225
31
39 38
37
B225
B106
1
2
B550
923
42
44
B225
40
2
13
33
14
45
6
PRND
T7
9
1
41
36
5
9
1
6
10
2
7
11
3
8
12
4
B12
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
19 20 21 22 23 24 25 26 27 28 29 30
789
10 11 12 13 14 15 16 17 18
123 456
B574C:
11 12
34
13 14
56
15 16
78
17 18
10
9
12
B572A:
B575
123
456789
10 11
12 13 14 15 16 17 18 19 20 21 22
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10791
B14
1
B23 B28
8
B550
822
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-6
ECM
FUSE
HOLDER
(BROWN)
INHIBITOR
SWITCH
STARTER
CUT
RELAY
FUSE HOLDER
BATTERY
MAIN SBF
IG RELAY 1
(PUSH BUTTON
START)
F/B No. 26
STARTER RELAY
(PUSH BUTTON START)
STARTER
RELAY 1
CLUTCH
START
SWITCH
F/B No. 21
KEYLESS
ACCESS CM
STARTER MOTOR
15WRX_STI_US_EN.book 286 ージ 20  
EN(w/o STI)(diag)-287
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK PUSH BUTTON IGNITION SWITCH.
Operate the push button ignition switch.
Does it operate smoothly with-
out catch?
Go to step 2. Replace the push
button ignition
switch. <Ref. to
SL-106, Push But-
ton Ignition
Switch.>
2 CHECK DTC.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, Clear Memory Mode.>
2) Start and idle the engine for three minutes
or more.
Is the same DTC as current
diagnosis output?
Go to step 3. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
3 CHECK HARNESS BETWEEN ECM AND
KEYLESS ACCESS CM.
1) Turn the ignition to OFF.
2) Disconnect the connector from ECM.
3) Turn the ignition to ON.
4) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(B134) No. 45 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power
supply in harness
between ECM con-
nector and keyless
access CM con-
nector.
Repair the poor
contact of ECM
connector.
15WRX_STI_US_EN.book 287 ージ 20  
EN(w/o STI)(diag)-288
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DN:DTC P0560 SYSTEM VOLTAGE
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-151, DTC P0560 SYSTEM VOLTAGE, Diagnostic Trou-
ble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
WP
OP
WP
OP
B72
B550
923
41
B225
36 37
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B550
215
B220
11
12
10
13
B134A:
E159C:
A32
A23
A38
A24
A12
B220 B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10792
WP
OP
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
B72
7856
3412
ECM
SBF-7
SBF-6
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
: WITHOUT PUSH BUTTON START
: WITH PUSH BUTTON START
BATTERY
MAIN
RELAY
FUSE HOLDER
M/B No. 13
F/B No. 12
(BROWN)
(GRAY)
IG RELAY 1
(PUSH BUTTON
START)
FUSE HOLDER
IGNITION
SWITCH
MAIN SBF
15WRX_STI_US_EN.book 288 ージ 20  
EN(w/o STI)(diag)-289
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to OFF.
2) Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B134) No. 23 (+) — Chassis ground (–):
Is the voltage 10 V or more? Repair the poor
contact of ECM
connector.
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
MAIN FUSE BOX CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance between ECM con-
nector and chassis ground.
Connector & terminal
(B134) No. 23 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 3. Repair the short
circuit to ground in
harness between
ECM connector
and battery termi-
nal.
3 CHECK FUSE NO. 13 (MAIN FUSE BOX). Is the fuse blown out? Replace the fuse. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and battery
Poor contact of
ECM connector
Poor contact of
battery terminal
15WRX_STI_US_EN.book 289 ージ 20  
EN(w/o STI)(diag)-290
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DO:DTC P0604 INTERNAL CONTROL MODULE RANDOM ACCESS MEMORY
(RAM) ERROR
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-152, DTC P0604 INTERNAL CONTROL MODULE
RANDOM ACCESS MEMORY (RAM) ERROR, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine does not start.
Engine stalls.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
DP:DTC P0605 INTERNAL CONTROL MODULE READ ONLY MEMORY (ROM)
ERROR
NOTE:
For the diagnostic procedure, refer to DTC P0606. <Ref. to EN(w/o STI)(diag)-291, DTC P0606 CONTROL
MODULE PROCESSOR, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
15WRX_STI_US_EN.book 290 ージ 20  
EN(w/o STI)(diag)-291
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DQ:DTC P0606 CONTROL MODULE PROCESSOR
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-154, DTC P0606 CONTROL MODULE PROCESSOR,
Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10810
A12
A24
10 11
B220
15 2
B550
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
C2
C1
1
4
2
3
5
6
B30
B18
B29
B17
E57
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
ECM
ELECTRONIC
THROTTLE
CONTROL
FUSE HOLDER
MAIN RELAY
BATTERY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 291 ージ 20  
EN(w/o STI)(diag)-292
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DR:DTC P060A INTERNAL CONTROL MODULE MONITORING PROCESSOR
PERFORMANCE
NOTE:
For the diagnostic procedure, refer to DTC P0606. <Ref. to EN(w/o STI)(diag)-291, DTC P0606 CONTROL
MODULE PROCESSOR, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
DS:DTC P060B INTERNAL CONTROL MODULE A/D PROCESSING PERFOR-
MANCE
NOTE:
For the diagnostic procedure, refer to DTC P0606. <Ref. to EN(w/o STI)(diag)-291, DTC P0606 CONTROL
MODULE PROCESSOR, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
Step Check Yes No
1 CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(B134) No. 12 (+) — Engine ground (–):
(B134) No. 24 (+) — Engine ground (–):
Is the voltage 10 — 13 V? Go to step 2. Repair the open or
ground short circuit
of power supply
circuit.
2 CHECK INPUT VOLTAGE OF ECM.
1) Start the engine.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(B134) No. 12 (+) — Engine ground (–):
(B134) No. 24 (+) — Engine ground (–):
Is the voltage 13 — 15 V? Go to step 3. Repair the open or
ground short circuit
of power supply
circuit.
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance of harness between
ECM connector and electronic throttle control
connector.
Connector & terminal
(E158) No. 18 — (E57) No. 2:
(E158) No. 30 — (E57) No. 3:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit of harness
between ECM con-
nector and elec-
tronic throttle
control connector.
4 CHECK ECM GROUND HARNESS.
1) Connect all connectors.
2) Turn the ignition to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(B134) No. 35 (+) — Engine ground (–):
(B134) No. 47 (+) — Engine ground (–):
(E159) No. 10 (+) — Engine ground (–):
(E159) No. 17 (+) — Engine ground (–):
(E159) No. 18 (+) — Engine ground (–):
(E159) No. 25 (+) — Engine ground (–):
(E159) No. 26 (+) — Engine ground (–):
Is the voltage less than 1 V? Check the connec-
tor for poor contact
and check the har-
ness. Replace the
ECM if no fault is
found. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
ground circuit
Loose engine
ground terminal
Poor contact of
coupling connector
15WRX_STI_US_EN.book 292 ージ 20  
EN(w/o STI)(diag)-293
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DT:DTC P0616 STARTER RELAY CIRCUIT LOW
1. MODEL WITHOUT PUSH BUTTON START
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-157, DTC P0616 STARTER RELAY CIRCUIT LOW, Di-
agnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, ENGINE
TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B72
7856
3412
MT
CVT
MT
CVT
21 7
B550
B134
B106
1
2
5
9
1
6
10
2
7
11
3
8
12
4
B12
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B14
1
EN-10818
MT
MT
CVT
1
3
2
B225
5
B14
9
T7
DNRP
6
T3B12
11
12
MT
CVT
CVT
1
B106
1
M
7
B72
3
4
5
2
14
8
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-6
ECM
BATTERY
IGNITION
SWITCH
F/B No. 21
MAIN SBF
CLUTCH START SWITCH
INHIBITOR SWITCH
STARTER MOTOR
STARTER
RELAY 1
(BROWN)
FUSE HOLDER
15WRX_STI_US_EN.book 293 ージ 20  
EN(w/o STI)(diag)-294
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2. MODEL WITH PUSH BUTTON START
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-157, DTC P0616 STARTER RELAY CIRCUIT LOW, Di-
agnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(w/o STI)(diag)-
85, List of Diagnos-
tic Trouble Code
(DTC).>
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
STARTER RELAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Remove the starter relay.
3) Disconnect the connectors from ECM and
starter motor.
4) Measure the resistance of harness between
ECM connector and starter relay connector.
Connector & terminal
(B134) No. 8 — (B225) No. 1:
NOTE:
For CVT model, place the select lever in “P”
range or “N” range.
Is the resistance less than 1 Ω? Go to step 3.NOTE:
Check the follow-
ing item and repair
or replace if neces-
sary.
Open circuit of
harness between
ECM connector
and starter relay
connector
Poor contact of
coupling connector
3 CHECK HARNESS BETWEEN ECM AND
STARTER RELAY CONNECTOR.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B134) No. 8 — Chassis ground:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of ECM
connector.
Repair the short
circuit to ground in
harness between
ECM connector
and starter relay
connector.
15WRX_STI_US_EN.book 294 ージ 20  
EN(w/o STI)(diag)-295
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
CVT
CVT
MT
CVT
MT
CVT
B23
12345
6789
10
CVT
CVT
721
MT
11
12
B12
T3
MT
MT
B134
B14
1
M
B574C:
B572A:
3
B576B575
21
A7
C6
1
B106
3
2
B225
5
28
30
29
B225
31
39 38
37
B225
B106
1
2
B550
923
42
44
B225
40
2
13
33
14
45
6
PRND
T7
9
1
41
36
5
9
1
6
10
2
7
11
3
8
12
4
B12
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
19 20 21 22 23 24 25 26 27 28 29 30
789
10 11 12 13 14 15 16 17 18
123 456
B574C:
11 12
34
13 14
56
15 16
78
17 18
10
9
12
B572A:
B575
123
456789
10 11
12 13 14 15 16 17 18 19 20 21 22
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10791
B14
1
B23 B28
8
B550
822
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-6
ECM
FUSE
HOLDER
(BROWN)
INHIBITOR
SWITCH
STARTER
CUT
RELAY
FUSE HOLDER
BATTERY
MAIN SBF
IG RELAY 1
(PUSH BUTTON
START)
F/B No. 26
STARTER RELAY
(PUSH BUTTON START)
STARTER
RELAY 1
CLUTCH
START
SWITCH
F/B No. 21
KEYLESS
ACCESS CM
STARTER MOTOR
15WRX_STI_US_EN.book 295 ージ 20  
EN(w/o STI)(diag)-296
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
STARTER RELAY CONNECTOR.
1) Turn the ignition to OFF.
2) Disconnect the connector from ECM.
3) Remove the starter relay.
4) Measure the resistance of harness between
ECM connector and starter relay connector.
NOTE:
For CVT model, place the select lever in “P”
range or “N” range.
Connector & terminal
(B134) No. 8 — (B225) No. 1:
Is the resistance less than 1 Ω? Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and starter relay
connector
Poor contact of
coupling connector
2 CHECK HARNESS BETWEEN ECM AND
STARTER RELAY CONNECTOR.
1) Disconnect the connector from starter
motor.
2) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(B134) No. 8 — Engine ground:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of ECM
connector.
Repair the short
circuit to ground in
harness between
ECM connector
and starter relay
connector.
15WRX_STI_US_EN.book 296 ージ 20  
EN(w/o STI)(diag)-297
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DU:DTC P0617 STARTER RELAY CIRCUIT HIGH
1. MODEL WITHOUT PUSH BUTTON START
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-158, DTC P0617 STARTER RELAY CIRCUIT HIGH, Di-
agnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, ENGINE
TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B72
7856
3412
MT
CVT
MT
CVT
21 7
B550
B134
B106
1
2
5
9
1
6
10
2
7
11
3
8
12
4
B12
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B14
1
EN-10818
MT
MT
CVT
1
3
2
B225
5
B14
9
T7
DNRP
6
T3B12
11
12
MT
CVT
CVT
1
B106
1
M
7
B72
3
4
5
2
14
8
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-6
ECM
BATTERY
IGNITION
SWITCH
F/B No. 21
MAIN SBF
CLUTCH START SWITCH
INHIBITOR SWITCH
STARTER MOTOR
STARTER
RELAY 1
(BROWN)
FUSE HOLDER
15WRX_STI_US_EN.book 297 ージ 20  
EN(w/o STI)(diag)-298
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2. MODEL WITH PUSH BUTTON START
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-158, DTC P0617 STARTER RELAY CIRCUIT HIGH, Di-
agnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
STARTER RELAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B134) No. 8 (+) — Chassis ground (–):
NOTE:
For CVT model, place the select lever in “P”
range or “N” range.
Is the voltage 10 V or more? Repair the short
circuit to power in
harness between
ECM connector
and starter relay
connector.
Repair the poor
contact of ECM
connector.
15WRX_STI_US_EN.book 298 ージ 20  
EN(w/o STI)(diag)-299
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
CVT
CVT
MT
CVT
MT
CVT
B23
12345
6789
10
CVT
CVT
721
MT
11
12
B12
T3
MT
MT
B134
B14
1
M
B574C:
B572A:
3
B576B575
21
A7
C6
1
B106
3
2
B225
5
28
30
29
B225
31
39 38
37
B225
B106
1
2
B550
923
42
44
B225
40
2
13
33
14
45
6
PRND
T7
9
1
41
36
5
9
1
6
10
2
7
11
3
8
12
4
B12
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
19 20 21 22 23 24 25 26 27 28 29 30
789
10 11 12 13 14 15 16 17 18
123 456
B574C:
11 12
34
13 14
56
15 16
78
17 18
10
9
12
B572A:
B575
123
456789
10 11
12 13 14 15 16 17 18 19 20 21 22
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10791
B14
1
B23 B28
8
B550
822
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-6
ECM
FUSE
HOLDER
(BROWN)
INHIBITOR
SWITCH
STARTER
CUT
RELAY
FUSE HOLDER
BATTERY
MAIN SBF
IG RELAY 1
(PUSH BUTTON
START)
F/B No. 26
STARTER RELAY
(PUSH BUTTON START)
STARTER
RELAY 1
CLUTCH
START
SWITCH
F/B No. 21
KEYLESS
ACCESS CM
STARTER MOTOR
15WRX_STI_US_EN.book 299 ージ 20  
EN(w/o STI)(diag)-300
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK STARTER MOTOR.
1) Turn the ignition to ON.
2) Check the starter motor condition.
Is the starter motor rotating? Go to step 2. Repair the short
circuit to power
supply.
NOTE:
In this case, repair
the following har-
nesses:
Short circuit to
power supply in
harness between
ECM connector
and starter relay
connector
Short circuit to
power supply in
harness between
ECM connector
and starter motor
Short circuit to
power supply in
harness between
starter relay con-
nector and starter
motor
2 CHECK HARNESS BETWEEN STARTER
CUT RELAY CONNECTOR AND STARTER
RELAY CONNECTOR.
1) Turn the ignition to OFF.
2) Disconnect the connector from starter
motor.
3) Remove the starter cut relay and starter
relay.
4) Turn the ignition to ON.
5) Measure the voltage between starter relay
connector and chassis ground.
Connector & terminal
(B225) No. 2 (+) — Chassis ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power
supply in harness
between starter cut
relay connector
and starter relay
connector.
Go to step 3.
3 CHECK STARTER CUT RELAY.
1) Connect the battery to starter cut relay ter-
minals No. 40 and No. 42.
2) Measure the resistance between starter cut
relay terminals.
Terminals
No. 41 — No. 44:
Is the resistance 1 MΩ or
more?
Go to step 6. Replace the starter
cut relay. <Ref. to
SL-116, Starter
Cut Relay.>
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
STARTER RELAY CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(B134) No. 14 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and starter relay
connector.
5 CHECK STARTER RELAY.
Measure the resistance between starter relay
terminals.
Terminals
No. 1 — No. 2:
Is the resistance 1 MΩ or
more?
Go to step 6. Replace the starter
relay. <Ref. to
EN(w/o STI)(diag)-
9, LOCATION,
Electrical Compo-
nent Location.>
15WRX_STI_US_EN.book 300 ージ 20  
EN(w/o STI)(diag)-301
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK HARNESS BETWEEN ECM, START-
ER RELAY CONNECTOR AND STARTER
MOTOR.
1) Disconnect the connector from ECM.
2) Turn the ignition to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(B134) No. 8 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power
supply.
NOTE:
In this case, repair
the following har-
nesses:
Short circuit to
power supply in
harness between
ECM connector
and starter relay
connector
Short circuit to
power supply in
harness between
ECM connector
and starter motor
Short circuit to
power supply in
harness between
starter relay con-
nector and starter
motor
Repair the poor
contact of ECM
connector.
Step Check Yes No
15WRX_STI_US_EN.book 301 ージ 20  
EN(w/o STI)(diag)-302
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DV:DTC P062D FUEL INJECTOR DRIVER CIRCUIT PERFORMANCE (BANK 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-159, DTC P062D FUEL INJECTOR DRIVER CIRCUIT
PERFORMANCE (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine does not start.
Engine stalls.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
2
E6
E5
E17
E16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
2
1
E5
B11
B23
B35
EN-10794
2
1
E16
2
1
E6
2
1
E17
B47
B12
B24
B36
B48
C18
C17
C10
A35
A47
16
15
E3
B22
C26
C25
B134A:
E158B:
C: E159
ECM
FUEL INJECTOR No. 4
FUEL INJECTOR No. 3
FUEL INJECTOR No. 2
FUEL INJECTOR No. 1
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 302 ージ 20  
EN(w/o STI)(diag)-303
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
#1 (E158) No. 11 — (E158) No. 12:
#2 (E158) No. 23 — (E158) No. 24:
#3 (E158) No. 35 — (E158) No. 36:
#4 (E158) No. 47 — (E158) No. 48:
Is resistance 1.89 — 2.31 Ω at
20°C (68°F)?
Go to step 4. Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Disconnect the connector from fuel injector.
2) Measure the resistance of harness between
ECM connector and defective fuel injector con-
nector.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Repair or replace
the following items.
Poor contact of
fuel injector con-
nector
Defective fuel
injector <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
4 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of ECM
connector.
Go to step 5.
15WRX_STI_US_EN.book 303 ージ 20  
EN(w/o STI)(diag)-304
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DW:DTC P062F INTERNAL CONTROL MODULE EEPROM ERROR
NOTE:
For the diagnostic procedure, refer to DTC P0606. <Ref. to EN(w/o STI)(diag)-291, DTC P0606 CONTROL
MODULE PROCESSOR, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
5 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Disconnect the connector from fuel injector.
2) Measure the resistance between ECM con-
nector and engine ground on defective fuel
injectors.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the faulty
fuel injector. <Ref.
to FU(w/o STI)-51,
Fuel Injector.>
Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
Step Check Yes No
15WRX_STI_US_EN.book 304 ージ 20  
EN(w/o STI)(diag)-305
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DX:DTC P0685 ECM/PCM POWER RELAY CONTROL CIRCUIT/OPEN
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-161, DTC P0685 ECM/PCM POWER RELAY CON-
TROL CIRCUIT/OPEN, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
WP
OP
WP
OP
B72
B550
923
41
B225
36 37
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B550
215
B220
11
12
10
13
B134A:
E159C:
A32
A23
A38
A24
A12
B220 B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10792
WP
OP
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
B72
7856
3412
ECM
SBF-7
SBF-6
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
: WITHOUT PUSH BUTTON START
: WITH PUSH BUTTON START
BATTERY
MAIN
RELAY
FUSE HOLDER
M/B No. 13
F/B No. 12
(BROWN)
(GRAY)
IG RELAY 1
(PUSH BUTTON
START)
FUSE HOLDER
IGNITION
SWITCH
MAIN SBF
15WRX_STI_US_EN.book 305 ージ 20  
EN(w/o STI)(diag)-306
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DY:DTC P0700 TRANSMISSION CONTROL SYSTEM (MIL REQUEST)
NOTE:
For the diagnostic procedure, refer to CVT section. <Ref. to CVT(diag)-2, Basic Diagnostic Procedure.>
Step Check Yes No
1 CHECK ECM CONNECTOR.
Check the connecting condition of ECM con-
nector.
Is the ECM connector correctly
connected?
Go to step 2. Connect the ECM
connector cor-
rectly.
2 CHECK HARNESS BETWEEN ECM AND
MAIN RELAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Remove the main relay.
3) Disconnect the connector from ECM.
4) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(B134) No. 38 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 3. Repair the short
circuit to ground in
harness between
ECM connector
and main relay
connector.
3 CHECK HARNESS BETWEEN ECM AND
MAIN RELAY CONNECTOR.
1) Install the main relay.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(B134) No. 12 (+) — Engine ground (–):
(B134) No. 24 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Short circuit to
power supply in
harness between
ECM connector
and main relay
connector
Defective main
relay
Repair the poor
contact of ECM
connector.
15WRX_STI_US_EN.book 306 ージ 20  
EN(w/o STI)(diag)-307
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
DZ:DTC P081A STARTER DISABLE CIRCUIT LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-163, DTC P081A STARTER DISABLE CIRCUIT LOW,
Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Failure of engine to start
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 307 ージ 20  
EN(w/o STI)(diag)-308
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
CVT
CVT
MT
CVT
MT
CVT
B23
12345
6789
10
CVT
CVT
721
MT
11
12
B12
T3
MT
MT
B134
B14
1
M
B574C:
B572A:
3
B576B575
21
A7
C6
1
B106
3
2
B225
5
28
30
29
B225
31
39 38
37
B225
B106
1
2
B550
923
42
44
B225
40
2
13
33
14
45
6
PRND
T7
9
1
41
36
5
9
1
6
10
2
7
11
3
8
12
4
B12
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
19 20 21 22 23 24 25 26 27 28 29 30
789
10 11 12 13 14 15 16 17 18
123 456
B574C:
11 12
34
13 14
56
15 16
78
17 18
10
9
12
B572A:
B575
123
456789
10 11
12 13 14 15 16 17 18 19 20 21 22
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10791
B14
1
B23 B28
8
B550
822
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-6
ECM
FUSE
HOLDER
(BROWN)
INHIBITOR
SWITCH
STARTER
CUT
RELAY
FUSE HOLDER
BATTERY
MAIN SBF
IG RELAY 1
(PUSH BUTTON
START)
F/B No. 26
STARTER RELAY
(PUSH BUTTON START)
STARTER
RELAY 1
CLUTCH
START
SWITCH
F/B No. 21
KEYLESS
ACCESS CM
STARTER MOTOR
15WRX_STI_US_EN.book 308 ージ 20  
EN(w/o STI)(diag)-309
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN STARTER RE-
LAY (PUSH BUTTON START) CONNECTOR
AND STARTER CUT RELAY CONNECTOR.
1) Turn the ignition to OFF.
2) Remove the starter relay (push button start)
and starter cut relay.
3) Measure the resistance of harness between
starter relay (push button start) connector and
starter cut relay connector.
Connector & terminal
(B225) No. 28 — (B225) No. 42:
Is the resistance less than 1 Ω? Go to step 2. Repair the open
circuit in harness
between starter
relay (push button
start) connector
and starter cut
relay connector.
2 CHECK HARNESS BETWEEN ECM AND
STARTER CUT RELAY CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness between
ECM connector and starter cut relay connector.
Connector & terminal
(B134) No. 13 — (B225) No. 40:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit of harness
between ECM con-
nector and starter
cut relay connec-
tor.
3 CHECK STARTER CUT RELAY.
1) Connect the battery to starter cut relay ter-
minals No. 40 and No. 42.
2) Measure the resistance between starter cut
relay terminals.
Terminals
No. 41 — No. 44:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of ECM
connector.
Replace the starter
cut relay. <Ref. to
SL-116, Starter
Cut Relay.>
15WRX_STI_US_EN.book 309 ージ 20  
EN(w/o STI)(diag)-310
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EA:DTC P0851 PARK/NEUTRAL SWITCH INPUT CIRCUIT LOW (AT MODEL)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-164, DTC P0851 PARK/NEUTRAL SWITCH INPUT
CIRCUIT LOW (AT MODEL), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK SELECT CABLE. Is there any fault in select
cable?
Repair or adjust
the select cable.
<Ref. to CS-42,
Select Cable.>
Go to step 2.
2 CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Place the select lever in other than “P” range
and “N” range.
3) Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B134) No. 33 (+) — Chassis ground (–):
Is the voltage 10 V or more? Repair the poor
contact of ECM
connector.
Go to step 3.
ECM
T2B25
1
2
B22
12
3
4
5678
9
10 11 12
1413 15 16
E3
B22
16
CVT
MT
B25
12
T3B12
11
12
22 8
B550
5
9
1
6
10
2
7
11
3
8
12
4
B12
B14
1
EN-10834
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
B134
33 6
1
M
B14
PRND
T7
9
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
INHIBITOR SWITCH
STARTER MOTOR
(BROWN)
FUSE HOLDER
NEUTRAL POSITION
SWITCH
15WRX_STI_US_EN.book 310 ージ 20  
EN(w/o STI)(diag)-311
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
3 CHECK HARNESS BETWEEN ECM AND
TRANSMISSION HARNESS CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
transmission harness connector (T3).
3) Measure the resistance between ECM con-
nector and chassis ground.
Connector & terminal
(B134) No. 33 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair the short
circuit to ground in
harness between
ECM connector
and transmission
harness connec-
tor.
4 CHECK TRANSMISSION HARNESS CON-
NECTOR.
1) Disconnect the connector from inhibitor
switch.
2) Measure the resistance between transmis-
sion harness connector and engine ground.
Connector & terminal
(T3) No. 12 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the inhibi-
tor switch. <Ref. to
CVT(TR690)-92,
Inhibitor Switch.>
Repair short cir-
cuit to ground in
harness between
transmission har-
ness connector
and inhibitor switch
connector.
Step Check Yes No
15WRX_STI_US_EN.book 311 ージ 20  
EN(w/o STI)(diag)-312
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EB:DTC P0851 NEUTRAL SWITCH INPUT CIRCUIT LOW (MT MODEL)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-165, DTC P0851 NEUTRAL SWITCH INPUT CIRCUIT
LOW (MT MODEL), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Place the shift lever in a position other than
neutral.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(B134) No. 33 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair the poor
contact of ECM
connector.
Go to step 2.
ECM
T2B25
1
2
B22
12
3
4
5678
9
10 11 12
1413 15 16
E3
B22
16
CVT
MT
B25
12
T3B12
11
12
22 8
B550
5
9
1
6
10
2
7
11
3
8
12
4
B12
B14
1
EN-10834
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
B134
33 6
1
M
B14
PRND
T7
9
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
INHIBITOR SWITCH
STARTER MOTOR
(BROWN)
FUSE HOLDER
NEUTRAL POSITION
SWITCH
15WRX_STI_US_EN.book 312 ージ 20  
EN(w/o STI)(diag)-313
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK HARNESS BETWEEN ECM AND
NEUTRAL POSITION SWITCH CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
neutral position switch.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(B134) No. 33 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the neu-
tral position switch.
<Ref. to
6MT(TY75)-45,
Switches and Har-
ness.>
Repair the short
circuit to ground
harness between
ECM connector
and neutral posi-
tion switch connec-
tor.
Step Check Yes No
15WRX_STI_US_EN.book 313 ージ 20  
EN(w/o STI)(diag)-314
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EC:DTC P0852 PARK/NEUTRAL SWITCH INPUT CIRCUIT HIGH (AT MODEL)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-166, DTC P0852 PARK/NEUTRAL SWITCH INPUT
CIRCUIT HIGH (AT MODEL), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK SELECT CABLE. Is there any fault in select
cable?
Repair or adjust
the select cable.
<Ref. to CS-42,
Select Cable.>
Go to step 2.
2 CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground with select lever at “P” range
and “N” range.
Connector & terminal
(B134) No. 33 (+) — Chassis ground (–):
Is the voltage less than 1 V? Repair the poor
contact of ECM
connector.
Go to step 3.
ECM
T2B25
1
2
B22
12
3
4
5678
9
10 11 12
1413 15 16
E3
B22
16
CVT
MT
B25
12
T3B12
11
12
22 8
B550
5
9
1
6
10
2
7
11
3
8
12
4
B12
B14
1
EN-10834
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
B134
33 6
1
M
B14
PRND
T7
9
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
INHIBITOR SWITCH
STARTER MOTOR
(BROWN)
FUSE HOLDER
NEUTRAL POSITION
SWITCH
15WRX_STI_US_EN.book 314 ージ 20  
EN(w/o STI)(diag)-315
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
3 CHECK HARNESS BETWEEN ECM AND IN-
HIBITOR SWITCH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
inhibitor switch.
3) Measure the resistance of harness between
ECM connector and inhibitor switch connector.
Connector & terminal
(B134) No. 33 — (T7) No. 6:
Is the resistance less than 1 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Blown out of fuse
Open circuit in
harness between
ECM connector
and inhibitor switch
connector
Poor contact of
coupling connector
4 CHECK INHIBITOR SWITCH GROUND LINE.
Measure the resistance of harness between
inhibitor switch connector and engine ground.
Connector & terminal
(T7) No. 9 — Engine ground:
Is the resistance less than 5 Ω? Replace the inhibi-
tor switch. <Ref. to
CVT(TR690)-92,
Inhibitor Switch.>
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
inhibitor switch
connector and
starter motor
ground line
Poor contact of
coupling connector
Poor contact of
starter motor con-
nector
Poor contact of
starter motor
ground
Starter motor
Step Check Yes No
15WRX_STI_US_EN.book 315 ージ 20  
EN(w/o STI)(diag)-316
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
ED:DTC P0852 NEUTRAL SWITCH INPUT CIRCUIT HIGH (MT MODEL)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-167, DTC P0852 NEUTRAL SWITCH INPUT CIRCUIT
HIGH (MT MODEL), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Place the shift lever in neutral.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(B134) No. 33 (+) — Engine ground (–):
Is the voltage less than 1 V? Repair the poor
contact of ECM
connector.
Go to step 2.
ECM
T2B25
1
2
B22
12
3
4
5678
9
10 11 12
1413 15 16
E3
B22
16
CVT
MT
B25
12
T3B12
11
12
22 8
B550
5
9
1
6
10
2
7
11
3
8
12
4
B12
B14
1
EN-10834
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
T7
1
78
69
2345
B134
33 6
1
M
B14
PRND
T7
9
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
INHIBITOR SWITCH
STARTER MOTOR
(BROWN)
FUSE HOLDER
NEUTRAL POSITION
SWITCH
15WRX_STI_US_EN.book 316 ージ 20  
EN(w/o STI)(diag)-317
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK HARNESS BETWEEN ECM AND
NEUTRAL POSITION SWITCH CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
neutral position switch.
3) Measure the resistance of harness between
ECM connector and neutral position switch con-
nector.
Connector & terminal
(B134) No. 33 — (B25) No. 2:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit in harness
between ECM con-
nector and trans-
mission harness
connector.
3 CHECK HARNESS BETWEEN NEUTRAL
POSITION SWITCH CONNECTOR AND
CHASSIS GROUND.
Measure the resistance of harness between
neutral position switch connector and chassis
ground.
Connector & terminal
(B25) No. 1 — Chassis ground:
Is the resistance less than 5 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
neutral position
switch connector
and chassis
ground
Poor contact of
coupling connector
4 CHECK NEUTRAL POSITION SWITCH.
1) Place the shift lever in neutral.
2) Measure the resistance between neutral
position switch connector terminals.
Connector & terminal
(T2) No. 1 — (T2) No. 2:
Is the resistance less than 1 Ω? Repair the poor
contact of neutral
position switch
connector.
Replace the neu-
tral position switch.
<Ref. to
6MT(TY75)-45,
Switches and Har-
ness.>
Step Check Yes No
15WRX_STI_US_EN.book 317 ージ 20  
EN(w/o STI)(diag)-318
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EE:DTC P1134 A/F SENSOR MICRO-COMPUTER PROBLEM
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-168, DTC P1134 A/F SENSOR MICRO-COMPUTER
PROBLEM, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
15WRX_STI_US_EN.book 318 ージ 20  
EN(w/o STI)(diag)-319
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EF:DTC P113A O2 SENSOR CIRCUIT (OPEN) (BANK1 SENSOR2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-169, DTC P113A O2 SENSOR CIRCUIT (OPEN)
(BANK1 SENSOR2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 319 ージ 20  
EN(w/o STI)(diag)-320
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
keep the engine speed at 3,000 rpm. (2 minutes
maximum)
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» 0.490 V or more?
Go to step 6. Go to step 3.
3 CHECK REAR OXYGEN SENSOR CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 42 — (E25) No. 3:
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 5. Repair the open
circuit of harness
between ECM con-
nector and rear
oxygen sensor
connector.
5 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 16 — Engine ground
(E158) No. 42 — Engine ground
Is the resistance 1 Ω or more? Go to step 6. Repair the short
circuit to ground in
harness between
ECM connector
and rear oxygen
sensor connector.
6 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items.
Looseness and improper fitting of exhaust
system parts
Damage (crack, hole etc.) of parts
Loose part and improper installation between
front oxygen (A/F) sensor and rear oxygen sen-
sor
Is there any fault in exhaust
system?
Repair or replace
faulty parts.
Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
15WRX_STI_US_EN.book 320 ージ 20  
EN(w/o STI)(diag)-321
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EG:DTC P1160 RETURN SPRING FAILURE
NOTE:
For the diagnostic procedure, refer to DTC P2101. <Ref. to EN(w/o STI)(diag)-423, DTC P2101 THROTTLE
ACTUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Procedure with Diagnos-
tic Trouble Code (DTC).>
15WRX_STI_US_EN.book 321 ージ 20  
EN(w/o STI)(diag)-322
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EH:DTC P1261 DI INJECTOR CIRCUIT / OPEN - (CYLINDER 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-171, DTC P1261 DI INJECTOR CIRCUIT / OPEN -
(CYLINDER 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
2
E6
E5
E17
E16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
2
1
E5
B11
B23
B35
EN-10794
2
1
E16
2
1
E6
2
1
E17
B47
B12
B24
B36
B48
C18
C17
C10
A35
A47
16
15
E3
B22
C26
C25
B134A:
E158B:
C: E159
ECM
FUEL INJECTOR No. 4
FUEL INJECTOR No. 3
FUEL INJECTOR No. 2
FUEL INJECTOR No. 1
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 322 ージ 20  
EN(w/o STI)(diag)-323
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EI: DTC P1262 DI INJECTOR CIRCUIT / OPEN - (CYLINDER 2)
NOTE:
For the diagnostic procedure, refer to DTC P1261. <Ref. to EN(w/o STI)(diag)-322, DTC P1261 DI INJEC-
TOR CIRCUIT / OPEN - (CYLINDER 1), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
EJ:DTC P1263 DI INJECTOR CIRCUIT / OPEN - (CYLINDER 3)
NOTE:
For the diagnostic procedure, refer to DTC P1261. <Ref. to EN(w/o STI)(diag)-322, DTC P1261 DI INJEC-
TOR CIRCUIT / OPEN - (CYLINDER 1), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
EK:DTC P1264 DI INJECTOR CIRCUIT / OPEN - (CYLINDER 4)
NOTE:
For the diagnostic procedure, refer to DTC P1261. <Ref. to EN(w/o STI)(diag)-322, DTC P1261 DI INJEC-
TOR CIRCUIT / OPEN - (CYLINDER 1), Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM ter-
minals on faulty fuel injectors.
Connector & terminal
#1 (E158) No. 11 — (E158) No. 12:
#2 (E158) No. 23 — (E158) No. 24:
#3 (E158) No. 35 — (E158) No. 36:
#4 (E158) No. 47 — (E158) No. 48:
Is resistance 1.89 — 2.31 Ω at
20°C (68°F)?
Go to step 2. Go to step 3.
2 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance between ECM and
engine ground on faulty injectors.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of ECM
connector.
Go to step 3.
3 CHECK FUEL INJECTOR.
Check the fuel injector on faulty cylinder. <Ref.
to FU(w/o STI)-70, INSPECTION, Fuel Injec-
tor.>
Are fuel injectors OK? Repair the open or
ground short circuit
in harness
between ECM con-
nector and fuel
injector connector.
Replace the faulty
fuel injector. <Ref.
to FU(w/o STI)-51,
Fuel Injector.>
15WRX_STI_US_EN.book 323 ージ 20  
EN(w/o STI)(diag)-324
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EL:DTC P1449 EVAPORATIVE EMISSION CONT. SYS. AIR FILTER CLOG
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-173, DTC P1449 EVAPORATIVE EMISSION CONT.
SYS. AIR FILTER CLOG, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK DRAIN TUBE A AND DRAIN PIPE
BETWEEN LEAK CHECK VALVE ASSEM-
BLY AND DRAIN FILTER.
Is the drain tube A or the drain
pipe between leak check valve
assembly and drain filter
clogged?
Replace the drain
tube A or the drain
pipe between leak
check valve
assembly and
drain filter. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.> <Ref.
to EC(w/o STI)-50,
Drain Filter.>
Go to step 3.
3 CHECK DRAIN FILTER. Is the drain filter clogged? Replace the drain
filter. <Ref. to
EC(w/o STI)-50,
Drain Filter.>
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
15WRX_STI_US_EN.book 324 ージ 20  
EN(w/o STI)(diag)-325
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EM:DTC P1451 EVAPORATIVE EMISSION CONT. SYS.
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-174, DTC P1451 EVAPORATIVE EMISSION CONT.
SYS., Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK DRAIN TUBE BETWEEN CANISTER
AND LEAK CHECK VALVE ASSEMBLY.
Is the drain tube between canis-
ter and leak check valve
assembly clogged?
Replace the drain
tube between the
canister and leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
Go to step 2.
2 CHECK HOSES BETWEEN CANISTER AND
FUEL TANK.
Are the hoses between the can-
ister and fuel tank clogged?
Replace the hoses
between the canis-
ter and fuel tank.
<Ref. to EC(w/o
STI)-8, Canister.>
<Ref. to FU(w/o
STI)-152, Fuel
Tan k. >
Replace the canis-
ter. <Ref. to EC(w/
o STI)-8, Canis-
ter.>
After the operation
is complete, go to
the next step. Go to
step 3.
3 CHECK EVAPORATIVE EMISSION CON-
TROL SYSTEM.
Perform drive cycle I. <Ref. to EN(w/o
STI)(diag)-56, DRIVE CYCLE I, PROCEDURE,
Drive Cycle.>
Is DTC P1451 displayed on the
display?
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
End.
15WRX_STI_US_EN.book 325 ージ 20  
EN(w/o STI)(diag)-326
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EN:DTC P1458 CPC2 SOLENOID VALVE (CIRCUIT LOW)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-175, DTC P1458 CPC2 SOLENOID VALVE (CIRCUIT
LOW), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 12 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Go to step 3.
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
12
E52
4
E3
B22
EN-10809
B550
215
11
B220
01
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
E159
4
E52
1
212
E4
B22
12
3
4
5678
9
10 11 12
1413 15 16
12
E4
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
PURGE CONTROL
SOLENOID VALVE 1
PURGE CONTROL
SOLENOID VALVE 2
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 326 ージ 20  
EN(w/o STI)(diag)-327
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
3 CHECK POWER SUPPLY TO PURGE CON-
TROL SOLENOID VALVE 2.
Measure the voltage between purge control
solenoid valve 2 connector and engine ground.
Connector & terminal
(E52) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the power
supply circuit.
4 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 2
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
purge control solenoid valve 2.
3) Measure the resistance between the purge
control solenoid valve 2 connector and engine
ground.
Connector & terminal
(E52) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the ground
short circuit of har-
ness between
ECM connector
and purge control
solenoid valve 2
connector.
5 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 2
CONNECTOR.
Measure the resistance of harness between
ECM connector and purge control solenoid
valve 2 connector.
Connector & terminal
(E159) No. 12 — (E52) No. 2:
Is the resistance less than 1 Ω? Go to step 6. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and purge control
solenoid valve 2
connector
Poor contact of
coupling connector
6 CHECK PURGE CONTROL SOLENOID
VALVE 2.
1) Remove the purge control solenoid valve 2.
2) Measure the resistance between purge con-
trol solenoid valve 2 terminals.
Terminals
No. 1 — No. 2:
Is the resistance 10 — 100 Ω? Repair the poor
contact of the
purge control sole-
noid valve 2 con-
nector.
Replace the purge
control solenoid
valve 2. <Ref. to
EC(w/o STI)-22,
Purge Control
Solenoid Valve.>
Step Check Yes No
15WRX_STI_US_EN.book 327 ージ 20  
EN(w/o STI)(diag)-328
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EO:DTC P1459 CPC2 SOLENOID VALVE (CIRCUIT HIGH)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-176, DTC P1459 CPC2 SOLENOID VALVE (CIRCUIT
HIGH), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 2
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
purge control solenoid valve 2.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 12 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
harness between
ECM connector
and purge control
solenoid valve 2
connector.
Go to step 2.
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
12
E52
4
E3
B22
EN-10809
B550
215
11
B220
01
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
E159
4
E52
1
212
E4
B22
12
3
4
5678
9
10 11 12
1413 15 16
12
E4
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
PURGE CONTROL
SOLENOID VALVE 1
PURGE CONTROL
SOLENOID VALVE 2
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 328 ージ 20  
EN(w/o STI)(diag)-329
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EP:DTC P1492 EGR SOLENOID VALVE SIGNAL #1 CIRCUIT MALFUNCTION
(LOW INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1498. <Ref. to EN(w/o STI)(diag)-330, DTC P1498 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
EQ:DTC P1493 EGR SOLENOID VALVE SIGNAL #1 CIRCUIT MALFUNCTION
(HIGH INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1499. <Ref. to EN(w/o STI)(diag)-332, DTC P1499 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
ER:DTC P1494 EGR SOLENOID VALVE SIGNAL #2 CIRCUIT MALFUNCTION
(LOW INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1498. <Ref. to EN(w/o STI)(diag)-330, DTC P1498 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
ES:DTC P1495 EGR SOLENOID VALVE SIGNAL #2 CIRCUIT MALFUNCTION
(HIGH INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1499. <Ref. to EN(w/o STI)(diag)-332, DTC P1499 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
ET:DTC P1496 EGR SOLENOID VALVE SIGNAL #3 CIRCUIT MALFUNCTION
(LOW INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1498. <Ref. to EN(w/o STI)(diag)-330, DTC P1498 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
EU:DTC P1497 EGR SOLENOID VALVE SIGNAL #3 CIRCUIT MALFUNCTION
(HIGH INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1499. <Ref. to EN(w/o STI)(diag)-332, DTC P1499 EGR SOLE-
NOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
2 CHECK PURGE CONTROL SOLENOID
VALVE 2.
1) Turn the ignition switch to OFF.
2) Measure the resistance between purge con-
trol solenoid valve 2 terminals.
Terminals
No. 1 — No. 2:
Is the resistance less than 1 Ω? Replace the purge
control solenoid
valve 2. <Ref. to
EC(w/o STI)-22,
Purge Control
Solenoid Valve.>
Repair the poor
contact of ECM
connector.
Step Check Yes No
15WRX_STI_US_EN.book 329 ージ 20  
EN(w/o STI)(diag)-330
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EV:DTC P1498 EGR SOLENOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION
(LOW INPUT)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-178, DTC P1498 EGR SOLENOID VALVE SIGNAL #4
CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
Engine breathing
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
4
E3
B22
EN-10811
E18
5
2
3
1
4
6
E159
B550
215
11
B220
01
3
1
2
645
E18
5
21
13
29
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B22
12
3
4
5678
9
10 11 12
1413 15 16
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(GRAY)
MAIN RELAY
BATTERY
FUSE HOLDER
EGR
CONTROL VALVE
15WRX_STI_US_EN.book 330 ージ 20  
EN(w/o STI)(diag)-331
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK POWER SUPPLY TO EGR CON-
TROL VALVE.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the EGR
control valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between EGR control
valve connector and engine ground.
Connector & terminal
(E18) No. 2 (+) — Engine ground (–):
(E18) No. 5 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
EGR control valve
and main relay
connector
Poor contact of
coupling connector
2 CHECK HARNESS BETWEEN ECM AND
EGR CONTROL VALVE CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and EGR control valve connector.
Connector & terminal
DTC P1492; (E159) No. 5 — (E18) No. 3:
DTC P1494; (E159) No. 21 — (E18) No. 1:
DTC P1496; (E159) No. 13 — (E18) No. 4:
DTC P1498; (E159) No. 29 — (E18) No. 6:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit of the har-
ness between the
ECM connector
and EGR control
valve connector.
3 CHECK HARNESS BETWEEN ECM AND
EGR CONTROL VALVE CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
DTC P1492; (E159) No. 5 — Engine
ground:
DTC P1494; (E159) No. 21 — Engine
ground:
DTC P1496; (E159) No. 13 — Engine
ground:
DTC P1498; (E159) No. 29 — Engine
ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair ground
short circuit of har-
ness between
ECM connector
and EGR control
valve connector.
4 CHECK FOR POOR CONTACT.
Check for poor contact between ECM connec-
tor and EGR control valve connector.
Is there poor contact in ECM or
EGR control valve connector?
Repair the poor
contact of ECM or
EGR control valve
connector.
Replace EGR con-
trol valve. <Ref. to
EC(w/o STI)-35,
EGR Control
Valve.>
15WRX_STI_US_EN.book 331 ージ 20  
EN(w/o STI)(diag)-332
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EW:DTC P1499 EGR SOLENOID VALVE SIGNAL #4 CIRCUIT MALFUNCTION
(HIGH INPUT)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-179, DTC P1499 EGR SOLENOID VALVE SIGNAL #4
CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
Engine breathing
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
4
E3
B22
EN-10811
E18
5
2
3
1
4
6
E159
B550
215
11
B220
01
3
1
2
645
E18
5
21
13
29
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B22
12
3
4
5678
9
10 11 12
1413 15 16
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(GRAY)
MAIN RELAY
BATTERY
FUSE HOLDER
EGR
CONTROL VALVE
15WRX_STI_US_EN.book 332 ージ 20  
EN(w/o STI)(diag)-333
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
EGR CONTROL VALVE CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
EGR control valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
DTC P1493; (E159) No. 5 (+) — Engine
ground (–):
DTC P1495; (E159) No. 21 (+) — Engine
ground (–):
DTC P1497; (E159) No. 13 (+) — Engine
ground (–):
DTC P1499; (E159) No. 29 (+) — Engine
ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power
supply in the har-
ness between the
ECM connector
and EGR control
valve connector.
Go to step 2.
2 CHECK EGR CONTROL VALVE.
Measure the resistance between EGR control
valve terminals.
Terminals
DTC P1493; No. 2 — No. 3:
DTC P1495; No. 2 — No. 1:
DTC P1497; No. 5 — No. 4:
DTC P1499; No. 5 — No. 6:
Is the resistance 20 Ω or more? Repair the poor
contact of ECM
connector.
Replace EGR con-
trol valve. <Ref. to
EC(w/o STI)-35,
EGR Control
Valve.>
15WRX_STI_US_EN.book 333 ージ 20  
EN(w/o STI)(diag)-334
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EX:DTC P1603 ENGINE STALL HISTORY
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-180, DTC P1603 ENGINE STALL HISTORY, Diagnostic
Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode. <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>
NOTE:
This DTC may be detected even if fault does not occur in the vehicle. If the customer does not ask for in-
spection, perform the clear memory mode without inspection and return the vehicle to the user.
15WRX_STI_US_EN.book 334 ージ 20  
EN(w/o STI)(diag)-335
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
9
E3 B22
78
5
6
34
2
1
B122
EN-10799
B3
123
4
5
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
*
*
B122
J/C
B3
1
B550
215
01
B220
11
2
3
4
B134A:
E158B:
A19
B5
A16
A28
5
*
SBF-7
ECM
*
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
: TERMINAL No. OPTIONAL
ARRANGEMENT
MAIN RELAY
BATTERY
FUSE HOLDER
MASS AIR FLOW &
INTAKE AIR TEMPERATURE SENSOR
(BROWN)
(BLACK)
15WRX_STI_US_EN.book 335 ージ 20  
EN(w/o STI)(diag)-336
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 336 ージ 20  
EN(w/o STI)(diag)-337
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
E158B:
E159C:
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
12
E8
E8
1
2
C27
B38
EN-10322
ECM
ENGINE COOLANT
TEMPERATURE
SENSOR
(GRAY)
(BLACK)
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
12
E52
4
E3
B22
EN-10809
B550
215
11
B220
01
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
E159
4
E52
1
212
E4
B22
12
3
4
5678
9
10 11 12
1413 15 16
12
E4
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
PURGE CONTROL
SOLENOID VALVE 1
PURGE CONTROL
SOLENOID VALVE 2
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 337 ージ 20  
EN(w/o STI)(diag)-338
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
E3B22
3
B550
215
01
B220
11
E38E37
12
E38
1
27
EN-10796
E159
1
215
E37
SBF-7
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
INTAKE
OIL CONTROL
SOLENOID LH
INTAKE
OIL CONTROL
SOLENOID RH
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
ECM
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
E3B22
3
B550
215
01
B220
11
E66E63
12
E63
1
223
EN-10795
E159
1
231
E66
SBF-7
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
EXHAUST
OIL CONTROL
SOLENOID LH
EXHAUST
OIL CONTROL
SOLENOID RH
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 338 ージ 20  
EN(w/o STI)(diag)-339
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK DTC. Is any other DTC displayed? Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(w/o STI)(diag)-
85, List of Diagnos-
tic Trouble Code
(DTC).>
Go to step 2.
2 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the value
in «Fuel Level».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Fuel Level»
16.4% or more?
Go to step 3. Fuel may be run
out. If the fault
occurs after refuel-
ing, continue the
diagnosis. Go to
step 3.
1
2
E6
E5
E17
E16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
2
1
E5
B11
B23
B35
EN-10794
2
1
E16
2
1
E6
2
1
E17
B47
B12
B24
B36
B48
C18
C17
C10
A35
A47
16
15
E3
B22
C26
C25
B134A:
E158B:
C: E159
ECM
FUEL INJECTOR No. 4
FUEL INJECTOR No. 3
FUEL INJECTOR No. 2
FUEL INJECTOR No. 1
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 339 ージ 20  
EN(w/o STI)(diag)-340
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
3 CHECK FREEZE FRAME DATA.
Read the value of «Control module voltage»
using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Control module
voltage» 11 V or more?
Go to step 4. Check the battery
and generator.
<Ref. to SC(w/o
STI)-51, INSPEC-
TION, Battery.>
<Ref. to SC(w/o
STI)-45, INSPEC-
TION, Generator.>
4 CHECK FOR MALFUNCTION OCCUR-
RENCE.
Did you ask the customer about
the driving condition and
engine speed status when the
fault occurred?
The engine
speed dropped
slowly and then the
engine stalled dur-
ing idling or decel-
eration: Go to step
5.
The engine
speed dropped
rapidly and then
the engine stalled
during idling or
deceleration: Go to
step 82.
The engine
stalled during
standing start,
acceleration, or
constant speed
driving: Go to step
89.
Ask the customer
about the driving
condition and
engine speed sta-
tus when fault
occurred.
5 CHECK FREEZE FRAME DATA.
1) Read the values of «Short term fuel trim
B1» and «Long term fuel trim B1», using the
Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
2) Obtain the sum values of «Short term fuel
trim B1» and «Long term fuel trim B1» in each
freeze frame data.
Is the sum value of «Short term
fuel trim B1» and «Long term
fuel trim B1» within ±15% in
each freeze frame data?
Go to step 56. More than 15%
in each freeze
frame data: Go to
step 6.
Less than –15%
in any one of
freeze frame data:
Go to step 40.
6 CHECK AIR INTAKE SYSTEM.
Check the installing condition of the air intake
system.
Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
<Ref. to IN(w/o
STI)-2, General
Description.>
Go to step 7.
7 CHECK PURGE CONTROL SOLENOID
VALVE.
Check purge control solenoid valve 1 and purge
control solenoid valve 2. <Ref. to EC(w/o STI)-
29, INSPECTION, Purge Control Solenoid
Valve.>
Are the purge control solenoid
valve 1 and the purge control
solenoid valve 2 normal?
Go to step 8. Replace the faulty
purge control sole-
noid valve. <Ref. to
EC(w/o STI)-22,
Purge Control
Solenoid Valve.>
Step Check Yes No
15WRX_STI_US_EN.book 340 ージ 20  
EN(w/o STI)(diag)-341
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
8 CHECK FREEZE FRAME DATA.
Read the value of «Stop Light Switch» using
Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Does the value of «Stop Light
Switch» indicate OFF in all
freeze frame data?
Go to step 11. Go to step 9.
9 CHECK CURRENT DATA.
1) Start the engine and warm up completely.
2) Read the value of «Short term fuel trim B1»
both when the brake pedal is released and
depressed using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Does the value of «Short term
fuel trim B1» with the brake
pedal depressed increase by
10% or more compared to
when the pedal is released?
Replace the brake
booster. <Ref. to
BR-55, Brake
Booster.>
Go to step 10.
10 CHECK CURRENT DATA.
1) Start the engine and warm up completely.
2) While reproducing the faulty condition of the
vehicle, read the values of «Short term fuel trim
B1» and «Long term fuel trim B1» using the
Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
3) Obtain the sum values of «Short term fuel
trim B1» and «Long term fuel trim B1».
Is the sum value of «Short term
fuel trim B1» and «Long term
fuel trim B1» within ±15%?
Go to step 11. Replace the brake
booster. <Ref. to
BR-55, Brake
Booster.>
11 CHECK IGNITION SYSTEM.
Check the ignition system. <Ref. to EN(w/o
STI)(diag)-80, IGNITION CONTROL SYSTEM,
Diagnostics for Engine Starting Failure.>
Is the ignition system normal? Go to step 12. Repair the ignition
system. <Ref. to
IG(w/o STI)-2,
General Descrip-
tion.>
12 CHECK FREEZE FRAME DATA.
Read the value of «A/F Sensor #1» using the
Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «A/F Sensor #1»
1.00 or more?
Go to step 17. Go to step 13.
13 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
Check the mass air flow and intake air tempera-
ture sensor. <Ref. to FU(w/o STI)-118,
INSPECTION, Mass Air Flow and Intake Air
Temperature Sensor.>
Is the mass air flow and intake
air temperature sensor normal?
Go to step 14. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 341 ージ 20  
EN(w/o STI)(diag)-342
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
14 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the mass air flow and intake air temperature
sensor.
3) Measure the resistance of harness between
ECM connector and the mass air flow and
intake air temperature sensor connector.
Connector & terminal
(B134) No. 16 — (B3) No. 3:
(B134) No. 28 — (B3) No. 2:
Is the resistance less than 1 Ω? Go to step 15. Repair the open
circuit of harness
between ECM con-
nector and the
mass air flow and
intake air tempera-
ture sensor con-
nector.
15 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(B134) No. 16 — Engine ground:
(B134) No. 28 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 16. Repair the ground
short circuit of har-
ness between
ECM connector
and the mass air
flow and intake air
temperature sen-
sor connector.
16 CHECK CURRENT DATA.
1) Start the engine and warm up completely.
2) Using the Subaru Select Monitor, read the
value of «Calculated load value», then compare
it with that of «Calculated load value» listed in
“Engine Current Data Display”. <Ref. to EN(w/o
STI)(diag)-37, DISPLAY CURRENT ENGINE
DATA, OPERATION, Subaru Select Monitor.>
NOTE:
The value of «Calculated load value» change
depending on how the engine internal parts set-
tle in. If the value is out of standard, judge it
again by comparing the vehicle with another
one with the same specifications and similar
conditions such as travel distance.
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Does the value of «Calculated
load value» falls between 90 —
110% of the value described in
the list?
Go to step 21. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
17 CHECK FRONT OXYGEN (A/F) SENSOR DA-
TA.
1) Start the engine and warm up completely.
2) Raise the engine speed up to 2,500 rpm and
maintain it for approx. three minutes.
3) Release the accelerator pedal and idle the
engine.
4) Using «Injection Quantity Control» in «Sys-
tem Operation Check Mode», read the value of
«A/F Sensor #1» at the increase rate of both
12% and –12%.
NOTE:
Perform the operation immediately after the
engine comes into idling condition, otherwise
the front oxygen (A/F) sensor will be cooled.
For detailed procedures, refer to “System Op-
eration Check Mode”. <Ref. to EN(w/o STI)(di-
ag)-62, System Operation Check Mode.>
Does the value of «A/F Sensor
#1» change to less than 0.88
at the increase rate of 12%,
and to 1.12 or more at the rate
of –12%?
Go to step 21. Go to step 18.
Step Check Yes No
15WRX_STI_US_EN.book 342 ージ 20  
EN(w/o STI)(diag)-343
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
18 CHECK POWER SUPPLY TO FRONT OXY-
GEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from front oxy-
gen (A/F) sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between front oxygen
(A/F) sensor connector and engine ground.
Connector & terminal
(E24) No. 3 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 19. Repair the power
supply line.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
A/F, oxygen sen-
sor relay and front
oxygen (A/F) sen-
sor connector
Poor contact of
A/F, oxygen sen-
sor relay connector
Poor contact of
coupling connector
Malfunction of A/
F, oxygen sensor
relay
19 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and front oxygen (A/F) sensor
connector.
Connector & terminal
(E158) No. 15 — (E24) No. 1:
(E158) No. 27 — (E24) No. 4:
(E158) No. 39 — (E24) No. 5:
(E159) No. 9 — (E24) No. 2:
Is the resistance less than 1 Ω? Go to step 20. Repair the open
circuit of harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
20 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 15 — Engine ground:
(E158) No. 27 — Engine ground:
(E158) No. 39 — Engine ground:
(E159) No. 9 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 21. Repair the short
circuit to ground in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector.
21 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Coolant Temp.» and «Ambient Temper-
ature».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Coolant Temp
120°C (248°F) or more? Or, is
the value of «Coolant Temp
lower than «Ambient Tempera-
ture» by 15°C (27°F) or more?
Go to step 22. Go to step 25.
22 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
Check the engine coolant temperature sensor.
<Ref. to FU(w/o STI)-94, INSPECTION, Engine
Coolant Temperature Sensor.>
Is the engine coolant tempera-
ture sensor normal?
Go to step 23. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 343 ージ 20  
EN(w/o STI)(diag)-344
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
23 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
engine coolant temperature sensor.
3) Measure the resistance of harness between
ECM connector and engine coolant tempera-
ture sensor connector.
Connector & terminal
(E159) No. 27 — (E8) No. 1:
(E158) No. 38 — (E8) No. 2:
Is the resistance less than 1 Ω? Go to step 24. Repair the open
circuit of the har-
ness between the
ECM connector
and engine coolant
temperature sen-
sor connector.
24 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 38 — Engine ground:
(E159) No. 27 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 25. Repair the short
circuit to ground in
harness between
ECM connector
and engine coolant
temperature sen-
sor connector.
25 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the value
in «Evap Purge Flow».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Evap Purge
Flow» 0% in all freeze frame
data?
Go to step 35. Go to step 26.
26 CHECK PURGE CONTROL SOLENOID
VALVE 1.
1) Select «CPC Solenoid Valve» from “Actua-
tor ON/OFF Operation” in “System Operation
Check Mode”.
NOTE:
For detailed procedures, refer to “System Oper-
ation Check Mode”. <Ref. to EN(w/o STI)(diag)-
62, System Operation Check Mode.>
2) Check if the ventilation changes according
to ON/OFF switching operation.
Does the ventilation of purge
control solenoid valve 1 change
correctly?
Go to step 30. Go to step 27.
27 CHECK POWER SUPPLY TO PURGE CON-
TROL SOLENOID VALVE 1 CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from purge con-
trol solenoid valve 1.
3) Turn the ignition switch to ON.
4) Measure the voltage between purge control
solenoid valve 1 connector and engine ground.
Connector & terminal
(E4) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 28. Repair the power
supply circuit.
28 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 1
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and purge control solenoid
valve 1 connector.
Connector & terminal
(E159) No. 4 — (E4) No. 2:
Is the resistance less than 1 Ω? Go to step
29. Repair the open
circuit in harness
between ECM con-
nector and purge
control solenoid
valve 1 connector.
Step Check Yes No
15WRX_STI_US_EN.book 344 ージ 20  
EN(w/o STI)(diag)-345
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
29 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 1
CONNECTOR.
Measure the resistance between the purge con-
trol solenoid valve 1 connector and engine
ground.
Connector & terminal
(E4) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 30. Repair the ground
short circuit of har-
ness between
ECM connector
and purge control
solenoid valve 1
connector.
30 CHECK PURGE CONTROL SOLENOID
VALVE 2.
1) Connect all connectors.
2) Select «CPC Solenoid 2» from “Actuator
ON/OFF Operation” in “System Operation
Check Mode”.
NOTE:
For detailed procedures, refer to “System Oper-
ation Check Mode”. <Ref. to EN(w/o STI)(diag)-
62, System Operation Check Mode.>
3) Check if the ventilation changes according
to ON/OFF switching operation.
Does the ventilation of purge
control solenoid valve 2 change
correctly?
Go to step 35. Go to step 31.
31 CHECK POWER SUPPLY TO PURGE CON-
TROL SOLENOID VALVE 2 CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from purge con-
trol solenoid valve 2.
3) Turn the ignition switch to ON.
4) Measure the voltage between purge control
solenoid valve 2 connector and engine ground.
Connector & terminal
(E52) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 32. Repair the power
supply circuit.
32 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 2
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and purge control solenoid
valve 2 connector.
Connector & terminal
(E159) No. 12 — (E52) No. 2:
Is the resistance less than 1 Ω? Go to step 33. Repair the open
circuit in harness
between ECM con-
nector and purge
control solenoid
valve 2 connector.
33 CHECK HARNESS BETWEEN ECM AND
PURGE CONTROL SOLENOID VALVE 2
CONNECTOR.
Measure the resistance between the purge con-
trol solenoid valve 2 connector and engine
ground.
Connector & terminal
(E52) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 34. Repair the ground
short circuit of har-
ness between
ECM connector
and purge control
solenoid valve 2
connector.
34 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
Step Check Yes No
15WRX_STI_US_EN.book 345 ージ 20  
EN(w/o STI)(diag)-346
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
35 CHECK OF FUEL PUMP.
1) Select «Fuel Pump» from “Actuator ON/
OFF Operation” in “System Operation Check
Mode”.
NOTE:
For detailed procedures, refer to “System Oper-
ation Check Mode”. <Ref. to EN(w/o STI)(diag)-
62, System Operation Check Mode.>
2) Check if operating sound occurs in the fuel
pump according to ON/OFF switching opera-
tion.
Does the fuel pump emit oper-
ating sound?
Go to step 37. Go to step 36.
36 CHECK OF FUEL PUMP.
Check fuel pump. <Ref. to FU(w/o STI)-172,
INSPECTION, Fuel Pump.>
Is the fuel pump normal? Check fuel pump
system. <Ref. to
EN(w/o STI)(diag)-
209, DTC P0230
FUEL PUMP PRI-
MARY CIRCUIT,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
Replace the fuel
pump. <Ref. to
FU(w/o STI)-168,
Fuel Pump.>
37 CHECK FUEL TANK.
Check if any foreign matters such as iron pow-
der exist in the fuel tank.
Is there any foreign matter in
the fuel tank?
Remove foreign
matter from the
fuel tank.
Go to step 38.
38 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 340 —
400 kPa (3.5 — 4.1 kgf/cm
2
, 49
— 58 psi)?
Go to step 39. Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
39 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Fuel Rail Pressure A» and «Com-
manded Fuel Rail Pressure A».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value in «Fuel Rail Pres-
sure A» synchronized with the
one in «Commanded Fuel Rail
Pressure A» in all freeze frame
data?
Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Check the high-
pressure fuel
pump. <Ref. to
FU(w/o STI)-82,
INSPECTION,
High Pressure
Fuel Pump.>
40 CHECK IGNITION SYSTEM.
Check the ignition system. <Ref. to EN(w/o
STI)(diag)-80, IGNITION CONTROL SYSTEM,
Diagnostics for Engine Starting Failure.>
Is the ignition system normal? Go to step 41. Repair the ignition
system. <Ref. to
IG(w/o STI)-2,
General Descrip-
tion.>
Step Check Yes No
15WRX_STI_US_EN.book 346 ージ 20  
EN(w/o STI)(diag)-347
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
41 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the value
of «Calculated load value», then compare it with
that of «Calculated load value» listed in “Engine
Current Data Display”. <Ref. to EN(w/o
STI)(diag)-37, DISPLAY CURRENT ENGINE
DATA, OPERATION, Subaru Select Monitor.>
NOTE:
The value of «Calculated load value» change
depending on how the engine internal parts set-
tle in. If the value is out of standard, judge it
again by comparing the vehicle with another
one with the same specifications and similar
conditions such as travel distance.
For detailed operation procedures, refer to
“Engine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Calculated load
value» 110% or more of the
value described in the list?
Go to step 43. Go to step 42.
42 CHECK FREEZE FRAME DATA.
Read the value of «A/F Sensor #1» using the
Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «A/F Sensor #1»
less than 1.00?
Go to step 47. Go to step 52.
43 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
Check the mass air flow and intake air tempera-
ture sensor. <Ref. to FU(w/o STI)-118,
INSPECTION, Mass Air Flow and Intake Air
Temperature Sensor.>
Is the mass air flow and intake
air temperature sensor normal?
Go to step 44. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
44 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the mass air flow and intake air temperature
sensor.
3) Measure the resistance of harness between
ECM connector and the mass air flow and
intake air temperature sensor connector.
Connector & terminal
(B134) No. 16 — (B3) No. 3:
(B134) No. 28 — (B3) No. 2:
Is the resistance less than 1 Ω? Go to step 45. Repair the open
circuit of harness
between ECM con-
nector and the
mass air flow and
intake air tempera-
ture sensor con-
nector.
45 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(B134) No. 16 — Engine ground:
(B134) No. 28 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 46. Repair the ground
short circuit of har-
ness between
ECM connector
and the mass air
flow and intake air
temperature sen-
sor connector.
Step Check Yes No
15WRX_STI_US_EN.book 347 ージ 20  
EN(w/o STI)(diag)-348
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
46 CHECK CURRENT DATA.
1) Start the engine and warm up completely.
2) Using the Subaru Select Monitor, read the
value of «Calculated load value», then compare
it with that of «Calculated load value» listed in
“Engine Current Data Display”. <Ref. to EN(w/o
STI)(diag)-37, DISPLAY CURRENT ENGINE
DATA, OPERATION, Subaru Select Monitor.>
NOTE:
The value of «Calculated load value» change
depending on how the engine internal parts set-
tle in. If the value is out of standard, judge it
again by comparing the vehicle with another
one with the same specifications and similar
conditions such as travel distance.
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Does the value of «Calculated
load value» falls between 90 —
110% of the value described in
the list?
Go to step 47. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
47 CHECK CURRENT DATA.
1) Start the engine and warm up completely.
2) Raise the engine speed up to 2,500 rpm and
maintain it for approx. three minutes.
3) Release the accelerator pedal and idle the
engine.
4) Using «Injection Quantity Control» in «Sys-
tem Operation Check Mode», read the value of
«A/F Sensor #1» at the increase rate of both
12% and –12%.
NOTE:
Perform the operation immediately after the
engine comes into idling condition, otherwise
the front oxygen (A/F) sensor will be cooled.
For detailed procedures, refer to “System Op-
eration Check Mode”. <Ref. to EN(w/o STI)(di-
ag)-62, System Operation Check Mode.>
Does the value of «A/F Sensor
#1» change to less than 0.88
at the increase rate of 12%,
and to 1.12 or more at the rate
of –12%?
Go to step 52. Go to step 48.
48 CHECK FREEZE FRAME DATA.
Read the value of «A/F Sensor #1 Resistance»
using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «A/F Sensor #1
Resistance» 500 Ω or more?
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
Go to step 49.
Step Check Yes No
15WRX_STI_US_EN.book 348 ージ 20  
EN(w/o STI)(diag)-349
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
49 CHECK POWER SUPPLY TO FRONT OXY-
GEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from front oxy-
gen (A/F) sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between front oxygen
(A/F) sensor connector and engine ground.
Connector & terminal
(E24) No. 3 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 50. Repair the power
supply line.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
A/F, oxygen sen-
sor relay and front
oxygen (A/F) sen-
sor connector
Poor contact of
A/F, oxygen sen-
sor relay connector
Poor contact of
coupling connector
Malfunction of A/
F, oxygen sensor
relay
50 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and front oxygen (A/F) sensor
connector.
Connector & terminal
(E158) No. 15 — (E24) No. 1:
(E158) No. 27 — (E24) No. 4:
(E158) No. 39 — (E24) No. 5:
(E159) No. 9 — (E24) No. 2:
Is the resistance less than 1 Ω? Go to step 51. Repair the open
circuit of harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
51 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 15 — Engine ground:
(E158) No. 27 — Engine ground:
(E158) No. 39 — Engine ground:
(E159) No. 9 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 52. Repair the short
circuit to ground in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector.
52 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Coolant Temp.» and «Ambient Temper-
ature».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Coolant Temp
120°C (248°F) or more? Or, is
the value of «Coolant Temp
lower than «Ambient Tempera-
ture» by 15°C (27°F) or more?
Go to step 53. Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
53 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
Check the engine coolant temperature sensor.
<Ref. to FU(w/o STI)-94, INSPECTION, Engine
Coolant Temperature Sensor.>
Is the engine coolant tempera-
ture sensor normal?
Go to step 54. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 349 ージ 20  
EN(w/o STI)(diag)-350
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
54 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
engine coolant temperature sensor.
3) Measure the resistance of harness between
ECM connector and engine coolant tempera-
ture sensor connector.
Connector & terminal
(E159) No. 27 — (E8) No. 1:
(E158) No. 38 — (E8) No. 2:
Is the resistance less than 1 Ω? Go to step 55. Repair the open
circuit of the har-
ness between the
ECM connector
and engine coolant
temperature sen-
sor connector.
55 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 38 — Engine ground:
(E159) No. 27 — Engine ground:
Is the resistance 1 MΩ or
more?
Even if DTC is
detected, it has
returned to a nor-
mal condition at
this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
Repair the short
circuit to ground in
harness between
ECM connector
and engine coolant
temperature sen-
sor connector.
56 CHECK IGNITION SYSTEM.
Check the ignition system. <Ref. to EN(w/o
STI)(diag)-80, IGNITION CONTROL SYSTEM,
Diagnostics for Engine Starting Failure.>
Is the ignition system normal? Go to step 57. Repair the ignition
system. <Ref. to
IG(w/o STI)-2,
General Descrip-
tion.>
Step Check Yes No
15WRX_STI_US_EN.book 350 ージ 20  
EN(w/o STI)(diag)-351
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
57 CHECK FREEZE FRAME DATA.
1) Using Subaru Select Monitor, read the val-
ues of «Idle Mass Air Flow Feedback correct»,
«ISC Learning Value» and «Idle dirty throttle
correct» in freeze frame data.
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
2) Obtain the sum value of «Idle Mass Air Flow
Feedback correct», «ISC Learning Value» and
«Idle dirty throttle correct».
3) Start the engine and warm up completely.
4) Using Subaru Select Monitor, read the val-
ues of «Idle Mass Air Flow Feedback correct»,
«ISC Learning Value» and «Idle dirty throttle
correct» in current data at normal idling.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
5) Obtain the sum value of «Idle Mass Air Flow
Feedback correct», «ISC Learning Value» and
«Idle dirty throttle correct».
Is the sum value of freeze frame
data less than 80% of the sum
value of current data?
Go to step 58. Go to step 60.
58 CHECK AIR INTAKE SYSTEM.
Check the installing condition of the air intake
system.
Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
<Ref. to IN(w/o
STI)-2, General
Description.>
Go to step 59.
59 CHECK AIR INTAKE SYSTEM.
Check the air intake system related parts.
Brake booster: <Ref. to BR-59, INSPEC-
TION, Brake Booster.>
Mass air flow and intake air temperature sen-
sor: <Ref. to FU(w/o STI)-118, INSPECTION,
Mass Air Flow and Intake Air Temperature Sen-
sor.>
PCV pipe: <Ref. to EC(w/o STI)-73, INSPEC-
TION, PCV Pipe.>
PCV connector: <Ref. to EC(w/o STI)-75,
INSPECTION, PCV Connector.>
PCV hose: <Ref. to EC(w/o STI)-77,
INSPECTION, PCV Hose.>
PCV hose assembly: <Ref. to EC(w/o STI)-
79, INSPECTION, PCV Hose Assembly.>
PCV valve: <Ref. to EC(w/o STI)-82,
INSPECTION, PCV Valve.>
Purge control solenoid valve 1 and purge
control solenoid valve 2: <Ref. to EC(w/o STI)-
29, INSPECTION, Purge Control Solenoid
Valve.>
Are all of the air intake system
related parts normal?
Go to step 77. Replace the parts
if defective.
Step Check Yes No
15WRX_STI_US_EN.book 351 ージ 20  
EN(w/o STI)(diag)-352
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
60 CHECK FREEZE FRAME DATA.
1) Using the Subaru Select Monitor, read the
values of the followings: «VVT Adv. Ang.
Amount R», «VVT Advance Target Angle
Amount R», «VVT Adv. Ang. Amount L», «VVT
Advance Target Angle Amount L», «Exh. VVT
Retard Ang. R», «Ex VVT Retard Target Angle
R», «Exh. VVT Retard Ang. L» and «Ex VVT
Retard Target Angle L».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
2) Using the Subaru Select Monitor, compare
the respective values between the followings:
«VVT Adv. Ang. Amount R» and «VVT Advance
Target Angle Amount R», «VVT Adv. Ang.
Amount L» and «VVT Advance Target Angle
Amount L», «Exh. VVT Retard Ang. R» and «Ex
VVT Retard Target Angle R», «Exh. VVT
Retard Ang. L» and «Ex VVT Retard Target
Angle L».
Does all of the advance angle
amount and retard angle
amount synchronize with their
target values?
Go to step 77. Diagnose the part
that does not syn-
chronize.
Intake RH: Go to
step 61.
Intake LH: Go to
step 65.
Exhaust RH: Go
to step 69.
Exhaust LH: Go
to step 73.
61 CHECK POWER SUPPLY TO THE INTAKE
OIL CONTROL SOLENOID RH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the intake oil
control solenoid RH.
3) Turn the ignition switch to ON.
4) Measure the voltage between intake oil con-
trol solenoid RH connector and engine ground.
Connector & terminal
(E38) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 62. Repair the power
supply circuit.
62 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID RH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and intake oil control solenoid
RH.
Connector & terminal
(E159) No. 7 — (E38) No. 2:
Is the resistance less than 1 Ω? Go to step 63. Repair the open
circuit in harness
between ECM con-
nector and intake
oil control solenoid
RH connector.
63 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID RH CON-
NECTOR.
Measure the resistance between intake oil con-
trol solenoid RH connector and engine ground.
Connector & terminal
(E38) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 64. Repair the short
circuit to ground in
harness between
ECM connector
and intake oil con-
trol solenoid RH
connector.
64 CHECK INTAKE OIL CONTROL SOLENOID
RH.
Check the intake oil control solenoid RH. <Ref.
to FU(w/o STI)-110, INSPECTION, Oil Control
Solenoid.>
Is the intake oil control solenoid
RH normal?
Replace the intake
cam sprocket RH.
<Ref. to ME(w/o
STI)-141, Cam
Sprocket.>
Replace the intake
oil control solenoid
RH. <Ref. to FU(w/
o STI)-108, Oil
Control Solenoid.>
Step Check Yes No
15WRX_STI_US_EN.book 352 ージ 20  
EN(w/o STI)(diag)-353
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
65 CHECK POWER SUPPLY TO THE INTAKE
OIL CONTROL SOLENOID LH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the intake oil
control solenoid LH.
3) Turn the ignition switch to ON.
4) Measure the voltage between intake oil con-
trol solenoid LH connector and engine ground.
Connector & terminal
(E37) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 66. Repair the power
supply circuit.
66 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID LH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and intake oil control solenoid
LH.
Connector & terminal
(E159) No. 15 — (E37) No. 2:
Is the resistance less than 1 Ω? Go to step 67. Repair the open
circuit in harness
between ECM con-
nector and intake
oil control solenoid
LH connector.
67 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID LH CON-
NECTOR.
Measure the resistance between intake oil con-
trol solenoid LH connector and engine ground.
Connector & terminal
(E37) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 68. Repair the short
circuit to ground in
harness between
ECM connector
and intake oil con-
trol solenoid LH
connector.
68 CHECK INTAKE OIL CONTROL SOLENOID
LH.
Check the intake oil control solenoid LH. <Ref.
to FU(w/o STI)-110, INSPECTION, Oil Control
Solenoid.>
Is the intake oil control solenoid
LH normal?
Replace the intake
cam sprocket LH.
<Ref. to ME(w/o
STI)-141, Cam
Sprocket.>
Replace the intake
oil control solenoid
LH. <Ref. to FU(w/
o STI)-108, Oil
Control Solenoid.>
69 CHECK POWER SUPPLY TO THE EXHAUST
OIL CONTROL SOLENOID RH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the exhaust
oil control solenoid RH.
3) Turn the ignition switch to ON.
4) Measure the voltage between exhaust oil
control solenoid RH connector and engine
ground.
Connector & terminal
(E63) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 70. Repair the power
supply circuit.
70 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID RH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and exhaust oil control solenoid
RH.
Connector & terminal
(E159) No. 23 — (E63) No. 2:
Is the resistance less than 1 Ω? Go to step 71. Repair the open
circuit in harness
between ECM con-
nector and exhaust
oil control solenoid
RH connector.
Step Check Yes No
15WRX_STI_US_EN.book 353 ージ 20  
EN(w/o STI)(diag)-354
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
71 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID RH CON-
NECTOR.
Measure the resistance between exhaust oil
control solenoid RH connector and engine
ground.
Connector & terminal
(E63) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 72. Repair the short
circuit to ground in
harness between
ECM connector
and exhaust oil
control solenoid
RH connector.
72 CHECK EXHAUST OIL CONTROL SOLE-
NOID RH.
Check the exhaust oil control solenoid RH.
<Ref. to FU(w/o STI)-110, INSPECTION, Oil
Control Solenoid.>
Is the exhaust oil control sole-
noid RH normal?
Replace the
exhaust cam
sprocket RH. <Ref.
to ME(w/o STI)-
141, Cam
Sprocket.>
Replace the
exhaust oil control
solenoid RH. <Ref.
to FU(w/o STI)-
108, Oil Control
Solenoid.>
73 CHECK POWER SUPPLY TO THE EXHAUST
OIL CONTROL SOLENOID LH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the exhaust
oil control solenoid LH.
3) Turn the ignition switch to ON.
4) Measure the voltage between exhaust oil
control solenoid LH connector and engine
ground.
Connector & terminal
(E66) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 74. Repair the power
supply circuit.
74 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID LH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and exhaust oil control solenoid
LH.
Connector & terminal
(E159) No. 31 — (E66) No. 2:
Is the resistance less than 1 Ω? Go to step 75. Repair the open
circuit in harness
between ECM con-
nector and exhaust
oil control solenoid
LH connector.
75 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID LH CON-
NECTOR.
Measure the resistance between exhaust oil
control solenoid LH connector and engine
ground.
Connector & terminal
(E66) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 76. Repair the short
circuit to ground in
harness between
ECM connector
and exhaust oil
control solenoid
LH connector.
76 CHECK EXHAUST OIL CONTROL SOLE-
NOID LH.
Check the exhaust oil control solenoid LH.
<Ref. to FU(w/o STI)-110, INSPECTION, Oil
Control Solenoid.>
Is the exhaust oil control sole-
noid LH normal?
Replace the
exhaust cam
sprocket LH. <Ref.
to ME(w/o STI)-
141, Cam
Sprocket.>
Replace the
exhaust oil control
solenoid LH. <Ref.
to FU(w/o STI)-
108, Oil Control
Solenoid.>
77 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
Check the engine coolant temperature sensor.
<Ref. to FU(w/o STI)-94, INSPECTION, Engine
Coolant Temperature Sensor.>
Is the engine coolant tempera-
ture sensor normal?
Go to step 78. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 354 ージ 20  
EN(w/o STI)(diag)-355
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
78 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
engine coolant temperature sensor.
3) Measure the resistance of harness between
ECM connector and engine coolant tempera-
ture sensor connector.
Connector & terminal
(E159) No. 27 — (E8) No. 1:
(E158) No. 38 — (E8) No. 2:
Is the resistance less than 1 Ω? Go to step 79. Repair the open
circuit of the har-
ness between the
ECM connector
and engine coolant
temperature sen-
sor connector.
79 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 38 — Engine ground:
(E159) No. 27 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 80. Repair the short
circuit to ground in
harness between
ECM connector
and engine coolant
temperature sen-
sor connector.
80 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
Check the mass air flow and intake air tempera-
ture sensor. <Ref. to FU(w/o STI)-118,
INSPECTION, Mass Air Flow and Intake Air
Temperature Sensor.>
Is the mass air flow and intake
air temperature sensor normal?
Go to step 81. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
81 CHECK MANIFOLD ABSOLUTE PRESSURE
AND INTAKE AIR TEMPERATURE SENSOR.
Check the manifold absolute pressure and
intake air temperature sensor. <Ref. to FU(w/o
STI)-121, INSPECTION, Manifold Absolute
Pressure and Intake Air Temperature Sensor.>
Is the manifold absolute pres-
sure and intake air temperature
sensor normal?
Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Check the manifold
absolute pressure
and intake air tem-
perature sensor.
<Ref. to FU(w/o
STI)-120, Manifold
Absolute Pressure
and Intake Air
Temperature Sen-
sor.>
82 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
fuel injectors.
3) Measure the resistance of harness between
ECM connector and fuel injector connector.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Go to step 83. Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
Step Check Yes No
15WRX_STI_US_EN.book 355 ージ 20  
EN(w/o STI)(diag)-356
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
83 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 84. Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
84 CHECK IGNITION SYSTEM.
Check the ignition system. <Ref. to EN(w/o
STI)(diag)-80, IGNITION CONTROL SYSTEM,
Diagnostics for Engine Starting Failure.>
Is the ignition system normal? Go to step 85. Repair the ignition
system. <Ref. to
IG(w/o STI)-2,
General Descrip-
tion.>
85 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «A/C Compressor Signal» and «Idle A/C
load correct».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Does the value of «A/C Com-
pressor Signal» indicate ON
output, and does the value of
«Idle A/C load correct»
increase?
Check the air con-
ditioner. <Ref. to
AC(diag)-12,
INSPECTION,
Diagnostics with
Phenomenon.>
<Ref. to AC(diag)-
2, PROCEDURE,
Basic Diagnostic
Procedure.>
Go to step 86.
86 CHECK FREEZE FRAME DATA.
1) Using the Subaru Select Monitor, read the
value of «Electric Load Feedback Val».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
2) Compare the value of «Electric Load Feed-
back Val» with that of «ISC Learning Value»,
which is described in “Engine Current Data Dis-
play”. <Ref. to EN(w/o STI)(diag)-37, DISPLAY
CURRENT ENGINE DATA, OPERATION, Sub-
aru Select Monitor.>
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Is the value of «Electric Load
Feedback Val» 20% or more of
«ISC Learning Value»?
Check the genera-
tor and power
assisted system.
<Ref. to SC(w/o
STI)-45, INSPEC-
TION, Generator.>
<Ref. to PS(diag)-
2, Basic Diagnostic
Procedure.>
Go to step 87.
87 CHECK FREEZE FRAME DATA.
1) Using the Subaru Select Monitor, read the
values of «Vehicle Speed», «Engine Speed»
and «AT turbine speed».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is there any freeze frame data
indicating that the value of
«Vehicle Speed» is less than 30
km/h (18.6 MPH), and that the
difference in values between
«Engine Speed» and «AT tur-
bine speed» is less than 100
rpm?
Repair the CVT.
<Ref. to
CVT(TR690)-3,
General Descrip-
tion.>
Go to step 88.
Step Check Yes No
15WRX_STI_US_EN.book 356 ージ 20  
EN(w/o STI)(diag)-357
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
88 CHECK DTC. Is DTC of CVT displayed?
<Ref. to CVT(diag)-16, OPER-
ATION, Read Diagnostic Trou-
ble Code (DTC).>
Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to
CVT(diag)-32, List
of Diagnostic Trou-
ble Code (DTC).>
Even if DTC is
detected, it has
returned to a nor-
mal condition at
this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
89 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Calculated load value» and «Relative
Throttle Pos.».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Calculated load
value» decreasing while that of
«Relative Throttle Pos.» is
increasing?
Go to step 90. Go to step 94.
90 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
Check the mass air flow and intake air tempera-
ture sensor. <Ref. to FU(w/o STI)-118,
INSPECTION, Mass Air Flow and Intake Air
Temperature Sensor.>
Is the mass air flow and intake
air temperature sensor normal?
Go to step 91. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
91 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the mass air flow and intake air temperature
sensor.
3) Measure the resistance of harness between
ECM connector and the mass air flow and
intake air temperature sensor connector.
Connector & terminal
(B134) No. 16 — (B3) No. 3:
(B134) No. 28 — (B3) No. 2:
Is the resistance less than 1 Ω? Go to step 92. Repair the open
circuit of harness
between ECM con-
nector and the
mass air flow and
intake air tempera-
ture sensor con-
nector.
92 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(B134) No. 16 — Engine ground:
(B134) No. 28 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 93. Repair the ground
short circuit of har-
ness between
ECM connector
and the mass air
flow and intake air
temperature sen-
sor connector.
Step Check Yes No
15WRX_STI_US_EN.book 357 ージ 20  
EN(w/o STI)(diag)-358
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
93 CHECK CURRENT DATA.
1) Start the engine and warm up completely.
2) Using the Subaru Select Monitor, read the
value of «Calculated load value», then compare
it with that of «Calculated load value» listed in
“Engine Current Data Display”. <Ref. to EN(w/o
STI)(diag)-37, DISPLAY CURRENT ENGINE
DATA, OPERATION, Subaru Select Monitor.>
NOTE:
The value of «Calculated load value» change
depending on how the engine internal parts set-
tle in. If the value is out of standard, judge it
again by comparing the vehicle with another
one with the same specifications and similar
conditions such as travel distance.
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Does the value of «Calculated
load value» falls between 90 —
110% of the value described in
the list?
Go to step 94. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
94 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
fuel injectors.
3) Measure the resistance of harness between
ECM connector and fuel injector connector.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Go to step 95. Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
95 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 96. Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
96 CHECK IGNITION SYSTEM.
Check the ignition system. <Ref. to EN(w/o
STI)(diag)-80, IGNITION CONTROL SYSTEM,
Diagnostics for Engine Starting Failure.>
Is the ignition system normal? Go to step 97. Repair the ignition
system. <Ref. to
IG(w/o STI)-2,
General Descrip-
tion.>
Step Check Yes No
15WRX_STI_US_EN.book 358 ージ 20  
EN(w/o STI)(diag)-359
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
97 CHECK OF FUEL PUMP.
1) Select «Fuel Pump» from “Actuator ON/
OFF Operation” in “System Operation Check
Mode”.
NOTE:
For detailed procedures, refer to “System Oper-
ation Check Mode”. <Ref. to EN(w/o STI)(diag)-
62, System Operation Check Mode.>
2) Check if operating sound occurs in the fuel
pump according to ON/OFF switching opera-
tion.
Does the fuel pump emit oper-
ating sound?
Go to step 99. Go to step 98.
98 CHECK OF FUEL PUMP.
Check fuel pump. <Ref. to FU(w/o STI)-172,
INSPECTION, Fuel Pump.>
Is the fuel pump normal? Check fuel pump
system. <Ref. to
EN(w/o STI)(diag)-
209, DTC P0230
FUEL PUMP PRI-
MARY CIRCUIT,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
Replace the fuel
pump. <Ref. to
FU(w/o STI)-168,
Fuel Pump.>
99 CHECK FUEL TANK.
Check if any foreign matters such as iron pow-
der exist in the fuel tank.
Is there any foreign matter in
the fuel tank?
Remove foreign
matter from the
fuel tank.
Go to step 100.
100 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 340 —
400 kPa (3.5 — 4.1 kgf/cm
2
, 49
— 58 psi)?
Go to step 101. Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
101 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Fuel Rail Pressure A» and «Com-
manded Fuel Rail Pressure A».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value in «Fuel Rail Pres-
sure A» synchronized with the
one in «Commanded Fuel Rail
Pressure A» in all freeze frame
data?
Go to step 102. Check the high-
pressure fuel
pump. <Ref. to
FU(w/o STI)-82,
INSPECTION,
High Pressure
Fuel Pump.>
102 CHECK ENGINE RUNNING CONDITION.
Check the engine running condition using
“Roughness monitor” in the Subaru Select
Monitor.
NOTE:
For detailed operation procedures, refer to “PC
application help for Subaru Select Monitor”.
Is there a large difference in the
speed between each cylinder?
It is possible that
the compression
pressure of the
engine is not suffi-
cient. Check the
engine. <Ref. to
ME(w/o STI)-352,
INSPECTION,
Engine Trouble in
General.>
Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Step Check Yes No
15WRX_STI_US_EN.book 359 ージ 20  
EN(w/o STI)(diag)-360
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EY:DTC P1604 STARTABILITY MALFUNCTION
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-181, DTC P1604 STARTABILITY MALFUNCTION, Di-
agnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode. <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>
NOTE:
This DTC may be detected even if fault does not occur in the vehicle. If the customer does not ask for in-
spection, perform the clear memory mode without inspection and return the vehicle to the user.
15WRX_STI_US_EN.book 360 ージ 20  
EN(w/o STI)(diag)-361
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
4
E3
B22
EN-10805
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
1
2
E158
19
E10
B22
12
3
4
5678
9
10 11 12
1413 15 16
E10
213
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
3
31
ECM
SBF-7
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
(BLACK)
CRANKSHAFT
POSITION SENSOR
MAIN RELAY
BATTERY
FUSE HOLDER
15WRX_STI_US_EN.book 361 ージ 20  
EN(w/o STI)(diag)-362
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
1
2
E6
E5
E17
E16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
2
1
E5
B11
B23
B35
EN-10794
2
1
E16
2
1
E6
2
1
E17
B47
B12
B24
B36
B48
C18
C17
C10
A35
A47
16
15
E3
B22
C26
C25
B134A:
E158B:
C: E159
ECM
FUEL INJECTOR No. 4
FUEL INJECTOR No. 3
FUEL INJECTOR No. 2
FUEL INJECTOR No. 1
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 362 ージ 20  
EN(w/o STI)(diag)-363
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
ECM
3
12
E34
E32
E33
E31
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
6
B220
7
B550
216
E3B22
2
3
2
1
E31
E159
8
16
24
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10793
3
2
1
E32
3
2
1
E33
3
2
1
E34
32
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
IGNITION COIL No. 4
IGNITION COIL No. 3
IGNITION COIL No. 2
IGNITION COIL No. 1
BATTERY
FUSE HOLDER
IG RELAY
(GRAY)
15WRX_STI_US_EN.book 363 ージ 20  
EN(w/o STI)(diag)-364
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
E3B22
3
B550
215
01
B220
11
E38E37
12
E38
1
27
EN-10796
E159
1
215
E37
SBF-7
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
INTAKE
OIL CONTROL
SOLENOID LH
INTAKE
OIL CONTROL
SOLENOID RH
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
ECM
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
E159
B22
12
3
4
5678
9
10 11 12
1413 15 16
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
E3B22
3
B550
215
01
B220
11
E66E63
12
E63
1
223
EN-10795
E159
1
231
E66
SBF-7
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
EXHAUST
OIL CONTROL
SOLENOID LH
EXHAUST
OIL CONTROL
SOLENOID RH
MAIN RELAY
BATTERY
FUSE HOLDER
(GRAY)
15WRX_STI_US_EN.book 364 ージ 20  
EN(w/o STI)(diag)-365
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
B22
12
3
4
5678
9
10 11 12
1413 15 16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
9
E3 B22
78
5
6
34
2
1
B122
EN-10799
B3
123
4
5
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
*
*
B122
J/C
B3
1
B550
215
01
B220
11
2
3
4
B134A:
E158B:
A19
B5
A16
A28
5
*
SBF-7
ECM
*
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
: TERMINAL No. OPTIONAL
ARRANGEMENT
MAIN RELAY
BATTERY
FUSE HOLDER
MASS AIR FLOW &
INTAKE AIR TEMPERATURE SENSOR
(BROWN)
(BLACK)
E158B:
E159C:
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
12
E8
E8
1
2
C27
B38
EN-10322
ECM
ENGINE COOLANT
TEMPERATURE
SENSOR
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 365 ージ 20  
EN(w/o STI)(diag)-366
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
4
E3
B22
EN-10806
B550
215
11
B220
01
E36
E35
213
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
3
E158
20
E35
1
2
3
21
E36
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
34
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BLACK)
INTAKE CAMSHAFT
POSITION SENSOR RH
INTAKE CAMSHAFT
POSITION SENSOR LH
MAIN RELAY
BATTERY
FUSE HOLDER
4
E3
B22
EN-10807
B550
215
11
B220
01
E65
E62
213
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
1
2
3
E158
32
E65
1
2
3
33
E62
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
34
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
ECM
(BLACK)
EXHAUST CAMSHAFT
POSITION SENSOR RH
EXHAUST CAMSHAFT
POSITION SENSOR LH
MAIN RELAY
BATTERY
FUSE HOLDER
15WRX_STI_US_EN.book 366 ージ 20  
EN(w/o STI)(diag)-367
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK DTC. Is any other DTC displayed? Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(w/o STI)(diag)-
85, List of Diagnos-
tic Trouble Code
(DTC).>
Go to step 2.
2 CHECK IMMOBILIZER.
Check the immobilizer. <Ref. to IM(diag)-2,
Basic Diagnostic Procedure.>
Is the immobilizer normal? Go to step 3. Repair the immobi-
lizer. <Ref. to
IM(diag)-2, Basic
Diagnostic Proce-
dure.>
3 CHECK FOR MALFUNCTION OCCUR-
RENCE.
Is it possible to reproduce the
faulty phenomenon or to iden-
tify the faulty condition?
Go to step 30. Go to step 4.
4 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Engine Speed» and «Control module
voltage».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Engine Speed»
0 rpm?
When the value
of «Control module
voltage» is less
than 5 V: Check
the battery. <Ref.
to SC(w/o STI)-51,
INSPECTION,
Battery.>
When the value
of «Control module
voltage» is 5 V or
more: Go to step 5.
When the value
of «Engine Speed»
is less than 250
rpm: Go to step 12.
When the value
of «Engine Speed»
is 250 rpm or more:
Go to step 20.
5 CHECK FREEZE FRAME DATA.
Read the value of «Control module voltage»
using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Control module
voltage» less than 9 V?
It is possible that
the engine friction
is too large. Check
the engine. <Ref.
to ME(w/o STI)-
352, INSPEC-
TION, Engine
Trouble in Gen-
eral.>
When the value
of «Control module
voltage» changes
in any one of
freeze frame data:
Go to step 6.
When the value
of «Control module
voltage» does not
change in all
freeze frame data:
Check the starter
motor circuit. <Ref.
to EN(w/o
STI)(diag)-67,
STARTER MOTOR
CIRCUIT, Diag-
nostics for Engine
Starting Failure.>
6 CHECK INSTALLATION CONDITION OF
CRANKSHAFT POSITION SENSOR.
Is the crankshaft position sen-
sor installed correctly?
Go to step 7. Install the crank-
shaft position sen-
sor correctly. <Ref.
to FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
15WRX_STI_US_EN.book 367 ージ 20  
EN(w/o STI)(diag)-368
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
7 CHECK CRANKSHAFT POSITION SENSOR.
Check the crankshaft position sensor. <Ref. to
FU(w/o STI)-100, INSPECTION, Crankshaft
Position Sensor.>
Is the crankshaft position sen-
sor normal?
Go to step 8. Replace the crank-
shaft position sen-
sor. <Ref. to FU(w/
o STI)-98, Crank-
shaft Position Sen-
sor.>
8 CHECK POWER SUPPLY TO CRANKSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the crank-
shaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 9. Repair the power
supply circuit.
9 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and crankshaft position sensor
connector.
Connector & terminal
(E158) No. 19 — (E10) No. 2:
(E158) No. 31 — (E10) No. 3:
Is the resistance less than 1 Ω? Go to step 10. Repair the open
circuit in the har-
ness between the
ECM connector
and crankshaft
position sensor
connector.
10 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
Measure the resistance between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 2 — Engine ground:
(E10) No. 3 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 11. Repair short cir-
cuit to ground in
harness between
ECM connector
and crankshaft
position sensor
connector.
11 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Replace the crankshaft position sensor.
<Ref. to FU(w/o STI)-98, Crankshaft Position
Sensor.>
2) Check that the fault is removed.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
12 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Coolant Temp.», «Ambient Tempera-
ture» and «Fuel Pump Duty».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Coolant Temp
120°C (248°F) or more? Or, is
the value of «Coolant Temp
lower than «Ambient Tempera-
ture» by 15°C (27°F) or more?
Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
When the value
of «Fuel Pump
Duty» is 60% or
more: Go to step
13.
When the value
of «Fuel Pump
Duty» is less than
60%: Check the
fuel pump system.
<Ref. to EN(w/o
STI)(diag)-209,
DTC P0230 FUEL
PUMP PRIMARY
CIRCUIT, Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
Step Check Yes No
15WRX_STI_US_EN.book 368 ージ 20  
EN(w/o STI)(diag)-369
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
13 CHECK OF FUEL PUMP.
1) Select «Fuel Pump» from “Actuator ON/
OFF Operation” in “System Operation Check
Mode”.
NOTE:
For detailed procedures, refer to “System Oper-
ation Check Mode”. <Ref. to EN(w/o STI)(diag)-
62, System Operation Check Mode.>
2) Check if operating sound occurs in the fuel
pump according to ON/OFF switching opera-
tion.
Does the fuel pump emit oper-
ating sound?
Go to step 15. Go to step 14.
14 CHECK OF FUEL PUMP.
Check fuel pump. <Ref. to FU(w/o STI)-172,
INSPECTION, Fuel Pump.>
Is the fuel pump normal? Check fuel pump
system. <Ref. to
EN(w/o STI)(diag)-
209, DTC P0230
FUEL PUMP PRI-
MARY CIRCUIT,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
Replace the fuel
pump. <Ref. to
FU(w/o STI)-168,
Fuel Pump.>
15 CHECK FUEL TANK.
Check if any foreign matters such as iron pow-
der exist in the fuel tank.
Is there any foreign matter in
the fuel tank?
Remove foreign
matter from the
fuel tank.
Go to step 16.
16 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 340 —
400 kPa (3.5 — 4.1 kgf/cm
2
, 49
— 58 psi)?
Go to step 17. Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
17 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Fuel Rail Pressure A» and «Com-
manded Fuel Rail Pressure A».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value in «Fuel Rail Pres-
sure A» synchronized with the
one in «Commanded Fuel Rail
Pressure A» in all freeze frame
data?
Go to step 18. Check the high-
pressure fuel
pump. <Ref. to
FU(w/o STI)-82,
INSPECTION,
High Pressure
Fuel Pump.>
Step Check Yes No
15WRX_STI_US_EN.book 369 ージ 20  
EN(w/o STI)(diag)-370
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
18 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
fuel injectors.
3) Measure the resistance of harness between
ECM connector and fuel injector connector.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Go to step 19. Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
19 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 29. Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
20 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Coolant Temp.», «Ambient Tempera-
ture» and «Engine Speed».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Coolant Temp
120°C (248°F) or more? Or, is
the value of «Coolant Temp
lower than «Ambient Tempera-
ture» by 15°C (27°F) or more?
Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
When the mini-
mum value of
«Engine Speed» is
less than 300 rpm:
Go to step 21.
When the mini-
mum value of
«Engine Speed» is
300 rpm or more: It
is possible that the
engine compres-
sion pressure is
not sufficient.
Check the engine.
<Ref. to ME(w/o
STI)-352,
INSPECTION,
Engine Trouble in
General.>
21 CHECK FUEL INJECTOR.
Check fuel injector. <Ref. to FU(w/o STI)-70,
INSPECTION, Fuel Injector.>
Is there any deposit in the fuel
injectors?
Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
Go to step 22.
22 CHECK FUEL TANK.
Check if any foreign matters such as iron pow-
der exist in the fuel tank.
Is there any foreign matter in
the fuel tank?
Remove foreign
matter from the
fuel tank.
Go to step 23.
Step Check Yes No
15WRX_STI_US_EN.book 370 ージ 20  
EN(w/o STI)(diag)-371
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
23 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the value
in «Coolant Temp.».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value of «Coolant Temp
40 — 90°C (104 — 194°F)?
Go to step 25. Go to step 24.
24 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure five minutes after the
engine is stopped. <Ref. to ME(w/o STI)-31,
INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
NOTE:
If the engine does not start, measure the fuel
pressure five minutes after cranking is complet-
ed.
Is the measured value 147 kPa
(1.5 kgf/cm
2
, 21 psi) or more?
Go to step 29. Replace the pres-
sure regulator.
<Ref. to FU(w/o
STI)-183, Fuel Fil-
ter.>
25 CHECK FUEL INJECTOR.
1) After the engine is stopped, scavenge inside
of the intake manifold by applying compressed
air.
2) Measure the HC concentration inside the
intake manifold 15 minutes after scavenging is
completed.
Is the HC concentration less
than 4,000 ppm?
Go to step 27. Go to step 26.
26 CHECK FUEL INJECTOR.
Check fuel injector. <Ref. to FU(w/o STI)-70,
INSPECTION, Fuel Injector.>
Are fuel injectors OK? Go to step 27. Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
27 CHECK THROTTLE BODY.
Check throttle body. <Ref. to FU(w/o STI)-16,
INSPECTION, Throttle Body.>
Is there any deposit in the throt-
tle body?
Replace the throt-
tle body. <Ref. to
FU(w/o STI)-15,
Throttle Body.>
Go to step 28.
28 CHECK AIR INTAKE SYSTEM.
Check the installing condition of the air intake
system.
Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
<Ref. to IN(w/o
STI)-2, General
Description.>
Go to step 29.
29 CHECK FOR MALFUNCTION OCCUR-
RENCE.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Go to step 30.
Step Check Yes No
15WRX_STI_US_EN.book 371 ージ 20  
EN(w/o STI)(diag)-372
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
30 CHECK FOR MALFUNCTION OCCUR-
RENCE.
Does cranking occur? When the engine
speed is abnormal
during cranking:
Go to step 37.
When an initial
combustion does
not occur: Go to
step 40.
When the engine
stalls immediately
after engine start:
Go to step 57.
When the engine
takes time to start:
Go to step 80.
Go to step 31.
31 CHECK FOR MALFUNCTION OCCUR-
RENCE.
Does the sound occur by a pro-
truding starter pinion gear dur-
ing cranking?
When the starter
motor does not
rotate: Go to step
32.
When the starter
motor rotates but
does not engage:
Go to step 34.
Go to step 35.
32 CHECK BATTERY.
Check the battery. <Ref. to SC(w/o STI)-51,
INSPECTION, Battery.>
Is the battery OK? Go to step 33. Charge or replace
the battery. <Ref.
to SC(w/o STI)-50,
Battery.>
33 CHECK ENGINE MAIN BODY.
Using the ST, rotate the crankshaft.
ST 18252AA000 CRANKSHAFT
SOCKET
Does the crankshaft rotate
smoothly?
Check the starter
motor. <Ref. to
SC(w/o STI)-24,
INSPECTION,
Starter.>
NOTE:
It is possible that
the engine friction
increased tempo-
rarily. Check if any
foreign matter is
mixed in engine oil.
If a foreign matter
is found, check the
engine. <Ref. to
ME(w/o STI)-352,
INSPECTION, En-
gine Trouble in
General.>
It is possible that
the engine friction
is too large. Check
the engine. <Ref.
to ME(w/o STI)-
352, INSPEC-
TION, Engine
Trouble in Gen-
eral.>
34 CHECK STARTER MOTOR.
Check the starter motor. <Ref. to SC(w/o STI)-
24, INSPECTION, Starter.>
Is there any wear or damage in
the starter pinion gear?
Repair the starter
motor. <Ref. to
SC(w/o STI)-7,
Starter.>
•CVT model:
Replace the torque
converter assem-
bly. <Ref. to
CVT(TR690)-140,
Torque Converter
Assembly.>
MT model:
Replace the fly-
wheel. <Ref. to CL-
15, Flywheel.>
Step Check Yes No
15WRX_STI_US_EN.book 372 ージ 20  
EN(w/o STI)(diag)-373
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
35 CHECK BATTERY.
Check the battery. <Ref. to SC(w/o STI)-51,
INSPECTION, Battery.>
Is the battery OK? Go to step 36. Charge or replace
the battery. <Ref.
to SC(w/o STI)-50,
Battery.>
36 CHECK STARTER MOTOR.
Check the starter motor. <Ref. to SC(w/o STI)-
24, INSPECTION, Starter.>
Is the starter motor OK? Check the starter
motor circuit. <Ref.
to EN(w/o
STI)(diag)-67,
STARTER MOTOR
CIRCUIT, Diag-
nostics for Engine
Starting Failure.>
Repair the starter
motor. <Ref. to
SC(w/o STI)-7,
Starter.>
37 CHECK CURRENT DATA.
Read the value of «Engine Speed» during
cranking using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Is the value of «Engine Speed»
300 rpm or more?
It is possible that
the compression
pressure of the
engine is not suffi-
cient. Check the
engine. <Ref. to
ME(w/o STI)-352,
INSPECTION,
Engine Trouble in
General.>
Go to step 38.
38 CHECK BATTERY.
Check the battery. <Ref. to SC(w/o STI)-51,
INSPECTION, Battery.>
Is the battery OK? Go to step 39. Charge or replace
the battery. <Ref.
to SC(w/o STI)-50,
Battery.>
39 CHECK ENGINE MAIN BODY.
Using the ST, rotate the crankshaft.
ST 18252AA000 CRANKSHAFT
SOCKET
Does the crankshaft rotate
smoothly?
Check the starter
motor. <Ref. to
SC(w/o STI)-24,
INSPECTION,
Starter.>
NOTE:
It is possible that
the engine friction
increased tempo-
rarily. Check if any
foreign matter is
mixed in engine oil.
If a foreign matter
is found, check the
engine. <Ref. to
ME(w/o STI)-352,
INSPECTION, En-
gine Trouble in
General.>
It is possible that
the engine friction
is too large. Check
the engine. <Ref.
to ME(w/o STI)-
352, INSPEC-
TION, Engine
Trouble in Gen-
eral.>
40 CHECK OPERATION OF EACH FUEL INJEC-
TOR.
Using a sound scope, check each fuel injector
for operation sound during cranking.
Does the fuel injector emit
operating sound?
Go to step 41. Go to step 54.
Step Check Yes No
15WRX_STI_US_EN.book 373 ージ 20  
EN(w/o STI)(diag)-374
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
41 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 340 —
400 kPa (3.5 — 4.1 kgf/cm
2
, 49
— 58 psi)?
Go to step 42. Go to step 52.
42 CHECK IGNITION CONDITION.
Check the ignition condition. <Ref. to EN(w/o
STI)(diag)-80, IGNITION CONTROL SYSTEM,
Diagnostics for Engine Starting Failure.>
Is the ignition condition nor-
mal?
Go to step 43. Go to step 46.
43 CHECK FOR MALFUNCTION OCCUR-
RENCE.
Check for the condition of fault occurrence.
Does the fault occur only within
approx. 15 to 120 minutes after
the engine is stopped?
Go to step 45. When the fault
occurs in two or
three minutes or a
long time after the
engine is stopped:
Go to step 44.
When the fault
occurrence pat-
tern is inconsis-
tent: Go to step 94.
44 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure five minutes after the
engine is stopped. <Ref. to ME(w/o STI)-31,
INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
NOTE:
If the engine does not start, measure the fuel
pressure five minutes after cranking is complet-
ed.
Is the measured value 147 kPa
(1.5 kgf/cm
2
, 21 psi) or more?
Go to step 94. Replace the pres-
sure regulator.
<Ref. to FU(w/o
STI)-183, Fuel Fil-
ter.>
45 CHECK FUEL INJECTOR.
1) After the engine is stopped, scavenge inside
of the intake manifold by applying compressed
air.
2) Measure the HC concentration inside the
intake manifold 15 minutes after scavenging is
completed.
Is the HC concentration less
than 4,000 ppm?
Go to step 94. Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
46 CHECK SPARK PLUG.
Check the spark plug. <Ref. to IG(w/o STI)-8,
INSPECTION, Spark Plug.>
Are the spark plugs normal? Go to step 47. Replace all spark
plugs on all cylin-
ders. <Ref. to
IG(w/o STI)-4,
Spark Plug.>
Step Check Yes No
15WRX_STI_US_EN.book 374 ージ 20  
EN(w/o STI)(diag)-375
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
47 CHECK CURRENT DATA.
Record the value of «Engine Speed» during
cranking using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Does the recorded value of
«Engine Speed» contain data
of 0 rpm?
It is possible that
temporary fault
occurs in the
crankshaft posi-
tion sensor circuit.
Check the crank-
shaft position sen-
sor circuit. <Ref. to
EN(w/o STI)(diag)-
236, DTC P0335
CRANKSHAFT
POSITION SEN-
SOR “A” CIRCUIT,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
Go to step 48.
48 CHECK IGNITION COIL POWER SUPPLY
CIRCUIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ignition coil.
3) Turn the ignition switch to ON.
4) Measure the voltage between ignition coil
connector and engine ground.
Connector & terminal
(E31) No. 1 (+) — Engine ground (–):
(E32) No. 1 (+) — Engine ground (–):
(E33) No. 1 (+) — Engine ground (–):
(E34) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 49. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit or
short circuit to
ground in power
supply circuit
Poor contact of
coupling connector
Blown out of fuse
49 CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness between
ECM connector and ignition coil connector.
Connector & terminal
(E159) No. 8 — (E31) No. 2:
(E159) No. 16 — (E32) No. 2:
(E159) No. 24 — (E33) No. 2:
(E159) No. 32 — (E34) No. 2:
Is the resistance less than 1 Ω? Go to step 50. Repair the open
circuit in harness
between ECM con-
nector and ignition
coil connector.
50 CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL CONNECTOR.
Measure the resistance of harness between
ECM connector and engine ground.
Connector & terminal
(E159) No. 8 — Engine ground:
(E159) No. 16 — Engine ground:
(E159) No. 24 — Engine ground:
(E159) No. 32 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 51. Repair the ground
short circuit of har-
ness between
ECM connector
and ignition coil
connector.
51 CHECK HARNESS OF IGNITION COIL
GROUND CIRCUIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between
ignition coil connector and engine ground.
Connector & terminal
(E31) No. 3 — Engine ground:
(E32) No. 3 — Engine ground:
(E33) No. 3 — Engine ground:
(E34) No. 3 — Engine ground:
Is the resistance less than 5 Ω? Replace the igni-
tion coil. <Ref. to
IG(w/o STI)-11,
Ignition Coil.> If the
fault occurs after
servicing, con-
tinue the diagno-
sis. Go to step 99.
Repair the open
circuit in harness
between ignition
coil connector and
engine grounding
terminal.
Step Check Yes No
15WRX_STI_US_EN.book 375 ージ 20  
EN(w/o STI)(diag)-376
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
52 CHECK OF FUEL PUMP.
1) Select «Fuel Pump» from “Actuator ON/
OFF Operation” in “System Operation Check
Mode”.
NOTE:
For detailed procedures, refer to “System Oper-
ation Check Mode”. <Ref. to EN(w/o STI)(diag)-
62, System Operation Check Mode.>
2) Check if operating sound occurs in the fuel
pump according to ON/OFF switching opera-
tion.
Does the fuel pump emit oper-
ating sound?
Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
Go to step 53.
53 CHECK OF FUEL PUMP.
Check fuel pump. <Ref. to FU(w/o STI)-172,
INSPECTION, Fuel Pump.>
Is the fuel pump normal? Check fuel pump
system. <Ref. to
EN(w/o STI)(diag)-
209, DTC P0230
FUEL PUMP PRI-
MARY CIRCUIT,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).> If the fault
occurs after servic-
ing, continue the
diagnosis. Go to
step 94.
Replace the fuel
pump. <Ref. to
FU(w/o STI)-168,
Fuel Pump.>
54 CHECK CURRENT DATA.
Record the value of «Engine Speed» during
cranking using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Does the recorded value of
«Engine Speed» contain data
of 0 rpm?
It is possible that
temporary fault
occurs in the
crankshaft posi-
tion sensor circuit.
Check the crank-
shaft position sen-
sor circuit. <Ref. to
EN(w/o STI)(diag)-
236, DTC P0335
CRANKSHAFT
POSITION SEN-
SOR “A” CIRCUIT,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
Go to step 55.
55 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
fuel injectors.
3) Measure the resistance of harness between
ECM connector and fuel injector connector.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Go to step 56. Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
Step Check Yes No
15WRX_STI_US_EN.book 376 ージ 20  
EN(w/o STI)(diag)-377
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
56 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
57 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
Check the mass air flow and intake air tempera-
ture sensor. <Ref. to FU(w/o STI)-118,
INSPECTION, Mass Air Flow and Intake Air
Temperature Sensor.>
Is the mass air flow and intake
air temperature sensor normal?
Go to step 58. Go to step 78.
58 CHECK AIR INTAKE SYSTEM.
Check the installing condition of the air intake
system.
Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
<Ref. to IN(w/o
STI)-2, General
Description.>
Go to step 59.
59 CHECK ELECTRONIC THROTTLE CON-
TROL.
1) Disconnect the connectors from electronic
throttle control.
2) Start the engine with the electronic throttle
control connector disconnected.
Does the engine start? Go to step 60. Go to step 61.
60 CHECK THROTTLE BODY.
Check throttle body. <Ref. to FU(w/o STI)-16,
INSPECTION, Throttle Body.>
Is there any deposit in the throt-
tle body?
Replace the throt-
tle body. <Ref. to
FU(w/o STI)-15,
Throttle Body.>
Go to step 61.
61 CHECK FREEZE FRAME DATA.
1) Using the Subaru Select Monitor, read the
values of the followings: «VVT Adv. Ang.
Amount R», «VVT Advance Target Angle
Amount R», «VVT Adv. Ang. Amount L», «VVT
Advance Target Angle Amount L», «Exh. VVT
Retard Ang. R», «Ex VVT Retard Target Angle
R», «Exh. VVT Retard Ang. L» and «Ex VVT
Retard Target Angle L».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
2) Using the Subaru Select Monitor, compare
the respective values between the followings:
«VVT Adv. Ang. Amount R» and «VVT Advance
Target Angle Amount R», «VVT Adv. Ang.
Amount L» and «VVT Advance Target Angle
Amount L», «Exh. VVT Retard Ang. R» and «Ex
VVT Retard Target Angle R», «Exh. VVT
Retard Ang. L» and «Ex VVT Retard Target
Angle L».
Does all of the advance angle
amount and retard angle
amount synchronize with their
target values?
Go to step 112. Diagnose the part
where there is dif-
ference of 10 deg
or more.
Intake RH: Go to
step 62.
Intake LH: Go to
step 66.
Exhaust RH: Go
to step 70.
Exhaust LH: Go
to step 74.
Step Check Yes No
15WRX_STI_US_EN.book 377 ージ 20  
EN(w/o STI)(diag)-378
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
62 CHECK POWER SUPPLY TO THE INTAKE
OIL CONTROL SOLENOID RH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the intake oil
control solenoid RH.
3) Turn the ignition switch to ON.
4) Measure the voltage between intake oil con-
trol solenoid RH connector and engine ground.
Connector & terminal
(E38) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 63. Repair the power
supply circuit.
63 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID RH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and intake oil control solenoid
RH.
Connector & terminal
(E159) No. 7 — (E38) No. 2:
Is the resistance less than 1 Ω? Go to step 64. Repair the open
circuit in harness
between ECM con-
nector and intake
oil control solenoid
RH connector.
64 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID RH CON-
NECTOR.
Measure the resistance between intake oil con-
trol solenoid RH connector and engine ground.
Connector & terminal
(E38) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 65. Repair the short
circuit to ground in
harness between
ECM connector
and intake oil con-
trol solenoid RH
connector.
65 CHECK INTAKE OIL CONTROL SOLENOID
RH.
Check the intake oil control solenoid RH. <Ref.
to FU(w/o STI)-110, INSPECTION, Oil Control
Solenoid.>
Is the intake oil control solenoid
RH normal?
Replace the intake
cam sprocket RH.
<Ref. to ME(w/o
STI)-141, Cam
Sprocket.>
Replace the intake
oil control solenoid
RH. <Ref. to FU(w/
o STI)-108, Oil
Control Solenoid.>
66 CHECK POWER SUPPLY TO THE INTAKE
OIL CONTROL SOLENOID LH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the intake oil
control solenoid LH.
3) Turn the ignition switch to ON.
4) Measure the voltage between intake oil con-
trol solenoid LH connector and engine ground.
Connector & terminal
(E37) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 67. Repair the power
supply circuit.
67 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID LH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and intake oil control solenoid
LH.
Connector & terminal
(E159) No. 15 — (E37) No. 2:
Is the resistance less than 1 Ω? Go to step 68. Repair the open
circuit in harness
between ECM con-
nector and intake
oil control solenoid
LH connector.
68 CHECK HARNESS BETWEEN ECM AND IN-
TAKE OIL CONTROL SOLENOID LH CON-
NECTOR.
Measure the resistance between intake oil con-
trol solenoid LH connector and engine ground.
Connector & terminal
(E37) No. 2 — Engine ground:
Is the resistance 1 M
Ω or
more?
Go to step 69. Repair the short
circuit to ground in
harness between
ECM connector
and intake oil con-
trol solenoid LH
connector.
Step Check Yes No
15WRX_STI_US_EN.book 378 ージ 20  
EN(w/o STI)(diag)-379
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
69 CHECK INTAKE OIL CONTROL SOLENOID
LH.
Check the intake oil control solenoid LH. <Ref.
to FU(w/o STI)-110, INSPECTION, Oil Control
Solenoid.>
Is the intake oil control solenoid
LH normal?
Replace the intake
cam sprocket LH.
<Ref. to ME(w/o
STI)-141, Cam
Sprocket.>
Replace the intake
oil control solenoid
LH. <Ref. to FU(w/
o STI)-108, Oil
Control Solenoid.>
70 CHECK POWER SUPPLY TO THE EXHAUST
OIL CONTROL SOLENOID RH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the exhaust
oil control solenoid RH.
3) Turn the ignition switch to ON.
4) Measure the voltage between exhaust oil
control solenoid RH connector and engine
ground.
Connector & terminal
(E63) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 71. Repair the power
supply circuit.
71 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID RH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and exhaust oil control solenoid
RH.
Connector & terminal
(E159) No. 23 — (E63) No. 2:
Is the resistance less than 1 Ω? Go to step 72. Repair the open
circuit in harness
between ECM con-
nector and exhaust
oil control solenoid
RH connector.
72 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID RH CON-
NECTOR.
Measure the resistance between exhaust oil
control solenoid RH connector and engine
ground.
Connector & terminal
(E63) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 73. Repair the short
circuit to ground in
harness between
ECM connector
and exhaust oil
control solenoid
RH connector.
73 CHECK EXHAUST OIL CONTROL SOLE-
NOID RH.
Check the exhaust oil control solenoid RH.
<Ref. to FU(w/o STI)-110, INSPECTION, Oil
Control Solenoid.>
Is the exhaust oil control sole-
noid RH normal?
Replace the
exhaust cam
sprocket RH. <Ref.
to ME(w/o STI)-
141, Cam
Sprocket.>
Replace the
exhaust oil control
solenoid RH. <Ref.
to FU(w/o STI)-
108, Oil Control
Solenoid.>
74 CHECK POWER SUPPLY TO THE EXHAUST
OIL CONTROL SOLENOID LH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the exhaust
oil control solenoid LH.
3) Turn the ignition switch to ON.
4) Measure the voltage between exhaust oil
control solenoid LH connector and engine
ground.
Connector & terminal
(E66) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 75. Repair the power
supply circuit.
Step Check Yes No
15WRX_STI_US_EN.book 379 ージ 20  
EN(w/o STI)(diag)-380
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
75 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID LH CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and exhaust oil control solenoid
LH.
Connector & terminal
(E159) No. 31 — (E66) No. 2:
Is the resistance less than 1 Ω? Go to step 76. Repair the open
circuit in harness
between ECM con-
nector and exhaust
oil control solenoid
LH connector.
76 CHECK HARNESS BETWEEN ECM AND EX-
HAUST OIL CONTROL SOLENOID LH CON-
NECTOR.
Measure the resistance between exhaust oil
control solenoid LH connector and engine
ground.
Connector & terminal
(E66) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 77. Repair the short
circuit to ground in
harness between
ECM connector
and exhaust oil
control solenoid
LH connector.
77 CHECK EXHAUST OIL CONTROL SOLE-
NOID LH.
Check the exhaust oil control solenoid LH.
<Ref. to FU(w/o STI)-110, INSPECTION, Oil
Control Solenoid.>
Is the exhaust oil control sole-
noid LH normal?
Replace the
exhaust cam
sprocket LH. <Ref.
to ME(w/o STI)-
141, Cam
Sprocket.>
Replace the
exhaust oil control
solenoid LH. <Ref.
to FU(w/o STI)-
108, Oil Control
Solenoid.>
78 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the mass air flow and intake air temperature
sensor.
3) Measure the resistance of harness between
ECM connector and the mass air flow and
intake air temperature sensor connector.
Connector & terminal
(B134) No. 16 — (B3) No. 3:
(B134) No. 28 — (B3) No. 2:
Is the resistance less than 1 Ω? Go to step 79. Repair the open
circuit of harness
between ECM con-
nector and the
mass air flow and
intake air tempera-
ture sensor con-
nector.
79 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(B134) No. 16 — Engine ground:
(B134) No. 28 — Engine ground:
Is the resistance 1 MΩ or
more?
Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.> If
the fault occurs
after servicing,
continue the diag-
nosis. Go to step
112.
Repair the ground
short circuit of har-
ness between
ECM connector
and the mass air
flow and intake air
temperature sen-
sor connector.
Step Check Yes No
15WRX_STI_US_EN.book 380 ージ 20  
EN(w/o STI)(diag)-381
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
80 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
Check the engine coolant temperature sensor.
<Ref. to FU(w/o STI)-94, INSPECTION, Engine
Coolant Temperature Sensor.>
Is the engine coolant tempera-
ture sensor normal?
Go to step 81. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.> If the
fault occurs after
servicing, replace
the ECM. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).> If
the fault still occurs
after replacing the
ECM, continue the
diagnosis. Go to
step 123.
81 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
engine coolant temperature sensor.
3) Measure the resistance of harness between
ECM connector and engine coolant tempera-
ture sensor connector.
Connector & terminal
(E159) No. 27 — (E8) No. 1:
(E158) No. 38 — (E8) No. 2:
Is the resistance less than 1 Ω? Go to step 82. Repair the open
circuit of the har-
ness between the
ECM connector
and engine coolant
temperature sen-
sor connector. If
the fault occurs
after servicing,
replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).> If the fault
still occurs after
replacing the ECM,
continue the diag-
nosis. Go to step
123.
82 CHECK HARNESS BETWEEN ECM AND EN-
GINE COOLANT TEMPERATURE SENSOR
CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 38 — Engine ground:
(E159) No. 27 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 83. Repair the short
circuit to ground in
harness between
ECM connector
and engine coolant
temperature sen-
sor connector. If
the fault occurs
after servicing,
replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).> If the fault
still occurs after
replacing the ECM,
continue the diag-
nosis. Go to step
123.
Step Check Yes No
15WRX_STI_US_EN.book 381 ージ 20  
EN(w/o STI)(diag)-382
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
83 CHECK CURRENT DATA.
1) Turn the ignition switch to ON. (engine OFF)
2) Read the values of «Long term fuel trim B1»
and «Atmosphere Pressure», using the Subaru
Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Is the value of «Long term fuel
trim B1» –25 — 25%, and
«Atmosphere Pressure» 80
kPa (600 mmHg, 23.6 inHg) or
more?
Go to step 86. Go to step 84.
84 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Perform the Clear Memory Mode. <Ref. to
EN(w/o STI)(diag)-61, Clear Memory Mode.>
2) Start the engine.
Does the engine start? Go to step 85. Go to step 86.
85 CHECK IDLE SPEED.
Check the idle speed.
Is the idle speed stable? Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.> If
the fault occurs
after servicing,
replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).> If the fault
still occurs after
replacing the ECM,
continue the diag-
nosis. Go to step
123.
Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.> If
the fault occurs
after servicing,
replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).> If the fault
still occurs after
replacing the ECM,
continue the diag-
nosis. Go to step
123.
86 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 340 —
400 kPa (3.5 — 4.1 kgf/cm
2
, 49
— 58 psi)?
Go to step 87. Go to step 93.
87 CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, read the val-
ues in «Fuel Rail Pressure A» and «Com-
manded Fuel Rail Pressure A».
NOTE:
For detailed operation procedures, refer to “En-
gine Freeze Frame Data Display”. <Ref. to
EN(w/o STI)(diag)-43, DISPLAY OF ENGINE
FREEZE FRAME DATA, OPERATION, Subaru
Select Monitor.>
Is the value in «Fuel Rail Pres-
sure A» synchronized with the
one in «Commanded Fuel Rail
Pressure A» in all freeze frame
data?
Go to step 88. Check the high-
pressure fuel
pump. <Ref. to
FU(w/o STI)-82,
INSPECTION,
High Pressure
Fuel Pump.>
Step Check Yes No
15WRX_STI_US_EN.book 382 ージ 20  
EN(w/o STI)(diag)-383
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
88 CHECK SPARK PLUG.
Check the spark plug. <Ref. to IG(w/o STI)-8,
INSPECTION, Spark Plug.>
Are all spark plug in all cylin-
ders normal?
Go to step 89. When spark
plugs in some cyl-
inders are faulty:
Replace the faulty
spark plugs of the
cylinders, then
check the ignition
system and fuel
system in the faulty
cylinders. <Ref. to
IG(w/o STI)-4,
Spark Plug.> If the
fault occurs after
servicing, con-
tinue the diagno-
sis. Go to step 123.
When all spark
plugs in all cylin-
ders are faulty:
Replace faulty
spark plugs in all
cylinders. <Ref. to
IG(w/o STI)-4,
Spark Plug.> If the
fault occurs after
servicing, con-
tinue the diagno-
sis. Go to step 123.
89 CHECK FOR MALFUNCTION OCCUR-
RENCE.
Check for the condition of fault occurrence.
Does the fault occur only within
approx. 15 to 120 minutes after
the engine is stopped?
Go to step 91. When the fault
occurs in two or
three minutes or a
long time after the
engine is stopped:
Go to step 90.
When the fault
occurrence pat-
tern is inconsis-
tent: Go to step
123.
90 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure five minutes after the
engine is stopped. <Ref. to ME(w/o STI)-31,
INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
NOTE:
If the engine does not start, measure the fuel
pressure five minutes after cranking is complet-
ed.
Is the measured value 147 kPa
(1.5 kgf/cm
2
, 21 psi) or more?
Go to step 123. Replace the pres-
sure regulator.
<Ref. to FU(w/o
STI)-183, Fuel Fil-
ter.>
Step Check Yes No
15WRX_STI_US_EN.book 383 ージ 20  
EN(w/o STI)(diag)-384
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
91 CHECK PURGE CONTROL SOLENOID
VALVE.
Check purge control solenoid valve 1 and purge
control solenoid valve 2. <Ref. to EC(w/o STI)-
29, INSPECTION, Purge Control Solenoid
Valve.>
Are the purge control solenoid
valve 1 and the purge control
solenoid valve 2 normal?
Go to step 92. Replace the faulty
purge control sole-
noid valve. <Ref. to
EC(w/o STI)-22,
Purge Control
Solenoid Valve.>
92 CHECK FUEL INJECTOR.
1) After the engine is stopped, scavenge inside
of the intake manifold by applying compressed
air.
2) Measure the HC concentration inside the
intake manifold 15 minutes after scavenging is
completed.
Is the HC concentration less
than 4,000 ppm?
Go to step 123. Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
93 CHECK OF FUEL PUMP.
Check fuel pump. <Ref. to FU(w/o STI)-172,
INSPECTION, Fuel Pump.>
Is the fuel pump normal? Check fuel pump
system. <Ref. to
EN(w/o STI)(diag)-
209, DTC P0230
FUEL PUMP PRI-
MARY CIRCUIT,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).> If the fault
occurs after servic-
ing, continue the
diagnosis. Go to
step 123.
Replace the fuel
pump. <Ref. to
FU(w/o STI)-168,
Fuel Pump.>
94 CHECK FUEL INJECTOR.
Check fuel injector. <Ref. to FU(w/o STI)-70,
INSPECTION, Fuel Injector.>
Are fuel injectors OK? Go to step 95. Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
95 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
fuel injectors.
3) Measure the resistance of harness between
ECM connector and fuel injector connector.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Go to step 96. Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
96 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
#1 (E158) No. 12 — Engine ground:
#1 (E158) No. 11 — Engine ground:
#2 (E158) No. 24 — Engine ground:
#2 (E158) No. 23 — Engine ground:
#3 (E158) No. 36 — Engine ground:
#3 (E158) No. 35 — Engine ground:
#4 (E158) No. 48 — Engine ground:
#4 (E158) No. 47 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 97. Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
Step Check Yes No
15WRX_STI_US_EN.book 384 ージ 20  
EN(w/o STI)(diag)-385
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
97 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Replace the crankshaft position sensor.
<Ref. to FU(w/o STI)-98, Crankshaft Position
Sensor.>
2) Check that the fault is removed.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Go to step 98.
98 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Replace the camshaft position sensor.
<Ref. to FU(w/o STI)-103, Camshaft Position
Sensor.>
2) Check that the fault is removed.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
99 CHECK INSTALLATION CONDITION OF
CRANKSHAFT POSITION SENSOR.
Is the crankshaft position sen-
sor installed correctly?
Go to step 100. Install the crank-
shaft position sen-
sor correctly. <Ref.
to FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
100 CHECK INSTALLATION CONDITION OF
CAMSHAFT POSITION SENSOR.
Is the camshaft position sensor
installed correctly?
Go to step 101. Install the cam-
shaft position sen-
sor correctly. <Ref.
to FU(w/o STI)-
104, INSTALLA-
TION, Camshaft
Position Sensor.>
101 CHECK POWER SUPPLY TO CRANKSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the crank-
shaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 102. Repair the power
supply circuit.
102 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and crankshaft position sensor
connector.
Connector & terminal
(E158) No. 19 — (E10) No. 2:
(E158) No. 31 — (E10) No. 3:
Is the resistance less than 1 Ω? Go to step 103. Repair the open
circuit in the har-
ness between the
ECM connector
and crankshaft
position sensor
connector.
103 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
Measure the resistance between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 2 — Engine ground:
(E10) No. 3 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 104. Repair short cir-
cuit to ground in
harness between
ECM connector
and crankshaft
position sensor
connector.
Step Check Yes No
15WRX_STI_US_EN.book 385 ージ 20  
EN(w/o STI)(diag)-386
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
104 CHECK POWER SUPPLY OF INTAKE CAM-
SHAFT POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the intake
camshaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between intake cam-
shaft position sensor connector and engine
ground.
Connector & terminal
(E35) No. 1 (+) — Engine ground (–):
(E36) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 105. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit or
short circuit to
ground in harness
between main re-
lay connector and
intake camshaft
position sensor
connector
Poor contact of
coupling connector
105 CHECK HARNESS BETWEEN ECM AND IN-
TAKE CAMSHAFT POSITION SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and intake camshaft position sensor
connector.
Connector & terminal
(E158) No. 21 — (E35) No. 2:
(E158) No. 34 — (E35) No. 3:
(E158) No. 20 — (E36) No. 2:
(E158) No. 34 — (E36) No. 3:
Is the resistance less than 1 Ω? Go to step 106. Repair the open
circuit in the har-
ness between
ECM connector
and intake cam-
shaft position sen-
sor connector.
106 CHECK HARNESS BETWEEN ECM AND IN-
TAKE CAMSHAFT POSITION SENSOR CON-
NECTOR.
Measure the resistance between intake cam-
shaft position sensor connector and engine
ground.
Connector & terminal
(E35) No. 2 — Engine ground:
(E36) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 107. Repair short cir-
cuit to ground in
the harness
between ECM con-
nector and intake
camshaft position
sensor connector.
107 CHECK POWER SUPPLY OF EXHAUST
CAMSHAFT POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the exhaust
camshaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between exhaust cam-
shaft position sensor connector and engine
ground.
Connector & terminal
(E62) No. 1 (+) — Engine ground (–):
(E65) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 108. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
main relay and ex-
haust camshaft po-
sition sensor
connector
Poor contact of
coupling connector
Step Check Yes No
15WRX_STI_US_EN.book 386 ージ 20  
EN(w/o STI)(diag)-387
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
108 CHECK HARNESS BETWEEN ECM AND EX-
HAUST CAMSHAFT POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and exhaust crankshaft position sensor
connector.
Connector & terminal
(E158) No. 32 — (E62) No. 2:
(E158) No. 34 — (E62) No. 3:
(E158) No. 33 — (E65) No. 2:
(E158) No. 34 — (E65) No. 3:
Is the resistance less than 1 Ω? Go to step 109. Repair the open
circuit in the har-
ness between
ECM connector
and exhaust cam-
shaft position sen-
sor connector.
109 CHECK HARNESS BETWEEN ECM AND EX-
HAUST CAMSHAFT POSITION SENSOR.
Measure the resistance between exhaust cam-
shaft position sensor connector and engine
ground.
Connector & terminal
(E62) No. 2 — Engine ground:
(E65) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 110. Repair short cir-
cuit to ground in
the harness
between ECM con-
nector and exhaust
camshaft position
sensor connector.
110 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Replace the crankshaft position sensor.
<Ref. to FU(w/o STI)-98, Crankshaft Position
Sensor.>
2) Check that the fault is removed.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Go to step 111.
111 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Replace the camshaft position sensor.
<Ref. to FU(w/o STI)-103, Camshaft Position
Sensor.>
2) Check that the fault is removed.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
112 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
Check the engine coolant temperature sensor.
<Ref. to FU(w/o STI)-94, INSPECTION, Engine
Coolant Temperature Sensor.>
Is the engine coolant tempera-
ture sensor normal?
Go to step 113. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
113 CHECK FUEL PRESSURE.
1) Read the value of «Fuel Rail Pressure A»
during cranking using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
2) Measure the fuel pressure five minutes after
the engine is stopped. <Ref. to ME(w/o STI)-31,
INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the value of «Fuel Rail Pres-
sure A» during cranking 304 —
353 kPa (3.1 — 3.6 kgf/cm
2
, 44
— 51 psi), and is the fuel pres-
sure five minutes after engine
stop 147 kPa (1.5 kgf/cm
2
, 21
psi) or more?
Go to step 114. Go to step 122.
Step Check Yes No
15WRX_STI_US_EN.book 387 ージ 20  
EN(w/o STI)(diag)-388
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
114 CHECK CURRENT DATA.
1) Turn the ignition switch to ON. (engine OFF)
2) Read the value of «Long term fuel trim B1»
using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Does the value of «Long term
fuel trim B1» fall within a range
of –15 — 15%?
Go to step 115. Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
115 CHECK FOR MALFUNCTION OCCUR-
RENCE.
Start the engine and check the idling speed.
Is the idling speed stable all
time?
It is possible that
the fault comes
from fuel. Replace
fuel.
Go to step 116.
116 CHECK INSTALLATION CONDITION OF
CRANKSHAFT POSITION SENSOR.
Is the crankshaft position sen-
sor installed correctly?
Go to step 117. Install the crank-
shaft position sen-
sor correctly. <Ref.
to FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
117 CHECK POWER SUPPLY TO CRANKSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the crank-
shaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 118. Repair the power
supply circuit.
118 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and crankshaft position sensor
connector.
Connector & terminal
(E158) No. 19 — (E10) No. 2:
(E158) No. 31 — (E10) No. 3:
Is the resistance less than 1 Ω? Go to step 119. Repair the open
circuit in the har-
ness between the
ECM connector
and crankshaft
position sensor
connector.
119 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
Measure the resistance between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 2 — Engine ground:
(E10) No. 3 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 120. Repair short cir-
cuit to ground in
harness between
ECM connector
and crankshaft
position sensor
connector.
120 CHECK COMPRESSION PRESSURE.
Check the compression pressure. <Ref. to
ME(w/o STI)-23, INSPECTION, Compres-
sion.>
Is the compression pressure
normal?
Go to step 121. Check the engine.
<Ref. to ME(w/o
STI)-352,
INSPECTION,
Engine Trouble in
General.>
Step Check Yes No
15WRX_STI_US_EN.book 388 ージ 20  
EN(w/o STI)(diag)-389
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
121 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Replace the crankshaft position sensor.
<Ref. to FU(w/o STI)-98, Crankshaft Position
Sensor.>
2) Check that the fault is removed.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Check the valve
timing. <Ref. to
ME(w/o STI)-116,
Timing Chain
Assembly.> When
the valve timing is
normal, replace
the ECM. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
122 CHECK OF FUEL PUMP.
Check fuel pump. <Ref. to FU(w/o STI)-172,
INSPECTION, Fuel Pump.>
Is the fuel pump normal? Check fuel pump
system. <Ref. to
EN(w/o STI)(diag)-
209, DTC P0230
FUEL PUMP PRI-
MARY CIRCUIT,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
Replace the fuel
pump. <Ref. to
FU(w/o STI)-168,
Fuel Pump.>
123 CHECK FUEL PRESSURE.
1) Read the value of «Fuel Rail Pressure A»
during cranking using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
2) Measure the fuel pressure five minutes after
the engine is stopped. <Ref. to ME(w/o STI)-31,
INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the value of «Fuel Rail Pres-
sure A» during cranking 304 —
353 kPa (3.1 — 3.6 kgf/cm
2
, 44
— 51 psi), and is the fuel pres-
sure five minutes after engine
stop 147 kPa (1.5 kgf/cm
2
, 21
psi) or more?
Go to step 124. Go to step 131.
124 CHECK CURRENT DATA.
1) Turn the ignition switch to ON. (engine OFF)
2) Read the value of «Long term fuel trim B1»
using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, DISPLAY CURRENT
ENGINE DATA, OPERATION, Subaru Select
Monitor.>
Does the value of «Long term
fuel trim B1» fall within a range
of –15 — 15%?
Go to step 125. Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
125 CHECK FOR MALFUNCTION OCCUR-
RENCE.
Start the engine and check the idling speed.
Is the idling speed stable all
time?
It is possible that
the fault comes
from fuel. Replace
fuel.
Go to step 126.
Step Check Yes No
15WRX_STI_US_EN.book 389 ージ 20  
EN(w/o STI)(diag)-390
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
126 CHECK INSTALLATION CONDITION OF
CRANKSHAFT POSITION SENSOR.
Is the crankshaft position sen-
sor installed correctly?
Go to step 127. Install the crank-
shaft position sen-
sor correctly. <Ref.
to FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
127 CHECK POWER SUPPLY TO CRANKSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the crank-
shaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 128. Repair the power
supply circuit.
128 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and crankshaft position sensor
connector.
Connector & terminal
(E158) No. 19 — (E10) No. 2:
(E158) No. 31 — (E10) No. 3:
Is the resistance less than 1 Ω? Go to step 129. Repair the open
circuit in the har-
ness between the
ECM connector
and crankshaft
position sensor
connector.
129 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
Measure the resistance between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 2 — Engine ground:
(E10) No. 3 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 130. Repair short cir-
cuit to ground in
harness between
ECM connector
and crankshaft
position sensor
connector.
130 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Replace the crankshaft position sensor.
<Ref. to FU(w/o STI)-98, Crankshaft Position
Sensor.>
2) Check that the fault is removed.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
131 CHECK OF FUEL PUMP.
Check fuel pump. <Ref. to FU(w/o STI)-172,
INSPECTION, Fuel Pump.>
Is the fuel pump normal? Go to step 132. Replace the fuel
pump. <Ref. to
FU(w/o STI)-168,
Fuel Pump.>
132 CHECK FUEL PUMP SYSTEM.
Check fuel pump system. <Ref. to EN(w/o
STI)(diag)-209, DTC P0230 FUEL PUMP PRI-
MARY CIRCUIT, Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
Is the fuel pump system nor-
mal?
Go to step 133. Repair the fuel
pump system.
<Ref. to EN(w/o
STI)(diag)-209,
DTC P0230 FUEL
PUMP PRIMARY
CIRCUIT, Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
Step Check Yes No
15WRX_STI_US_EN.book 390 ージ 20  
EN(w/o STI)(diag)-391
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
133 CHECK PURGE CONTROL SOLENOID
VALVE.
Check purge control solenoid valve 1 and purge
control solenoid valve 2. <Ref. to EC(w/o STI)-
29, INSPECTION, Purge Control Solenoid
Valve.>
Are the purge control solenoid
valve 1 and the purge control
solenoid valve 2 normal?
Go to step 134. Replace the faulty
purge control sole-
noid valve. <Ref. to
EC(w/o STI)-22,
Purge Control
Solenoid Valve.>
134 CHECK FUEL INJECTOR.
1) After the engine is stopped, scavenge inside
of the intake manifold by applying compressed
air.
2) Measure the HC concentration inside the
intake manifold 15 minutes after scavenging is
completed.
Is the HC concentration less
than 4,000 ppm?
Go to step 135. Replace the fuel
injector. <Ref. to
FU(w/o STI)-51,
Fuel Injector.>
135 CHECK INTAKE VALVE.
Check the intake valve. <Ref. to ME(w/o STI)-
236, INSPECTION, Cylinder Head.>
Is there any deposit in the
intake valve?
Clean the intake
valve. <Ref. to
ME(w/o STI)-215,
Cylinder Head.>
Go to step 136.
136 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
Check the engine coolant temperature sensor.
<Ref. to FU(w/o STI)-94, INSPECTION, Engine
Coolant Temperature Sensor.>
Is the engine coolant tempera-
ture sensor normal?
Go to step 137. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
137 CHECK INSTALLATION CONDITION OF
CRANKSHAFT POSITION SENSOR.
Is the crankshaft position sen-
sor installed correctly?
Go to step 138. Install the crank-
shaft position sen-
sor correctly. <Ref.
to FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
138 CHECK INSTALLATION CONDITION OF
CAMSHAFT POSITION SENSOR.
Is the camshaft position sensor
installed correctly?
Go to step 139. Install the cam-
shaft position sen-
sor correctly. <Ref.
to FU(w/o STI)-
104, INSTALLA-
TION, Camshaft
Position Sensor.>
139 CHECK POWER SUPPLY TO CRANKSHAFT
POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the crank-
shaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 140. Repair the power
supply circuit.
140 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and crankshaft position sensor
connector.
Connector & terminal
(E158) No. 19 — (E10) No. 2:
(E158) No. 31 — (E10) No. 3:
Is the resistance less than 1 Ω? Go to step 141. Repair the open
circuit in the har-
ness between the
ECM connector
and crankshaft
position sensor
connector.
Step Check Yes No
15WRX_STI_US_EN.book 391 ージ 20  
EN(w/o STI)(diag)-392
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
141 CHECK HARNESS BETWEEN ECM AND
CRANKSHAFT POSITION SENSOR CON-
NECTOR.
Measure the resistance between crankshaft
position sensor connector and engine ground.
Connector & terminal
(E10) No. 2 — Engine ground:
(E10) No. 3 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 142. Repair short cir-
cuit to ground in
harness between
ECM connector
and crankshaft
position sensor
connector.
142 CHECK POWER SUPPLY OF INTAKE CAM-
SHAFT POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the intake
camshaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between intake cam-
shaft position sensor connector and engine
ground.
Connector & terminal
(E35) No. 1 (+) — Engine ground (–):
(E36) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 143. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit or
short circuit to
ground in harness
between main re-
lay connector and
intake camshaft
position sensor
connector
Poor contact of
coupling connector
143 CHECK HARNESS BETWEEN ECM AND IN-
TAKE CAMSHAFT POSITION SENSOR CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and intake camshaft position sensor
connector.
Connector & terminal
(E158) No. 21 — (E35) No. 2:
(E158) No. 34 — (E35) No. 3:
(E158) No. 20 — (E36) No. 2:
(E158) No. 34 — (E36) No. 3:
Is the resistance less than 1 Ω? Go to step 144. Repair the open
circuit in the har-
ness between
ECM connector
and intake cam-
shaft position sen-
sor connector.
144 CHECK HARNESS BETWEEN ECM AND IN-
TAKE CAMSHAFT POSITION SENSOR CON-
NECTOR.
Measure the resistance between intake cam-
shaft position sensor connector and engine
ground.
Connector & terminal
(E35) No. 2 — Engine ground:
(E36) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 145. Repair short cir-
cuit to ground in
the harness
between ECM con-
nector and intake
camshaft position
sensor connector.
145 CHECK POWER SUPPLY OF EXHAUST
CAMSHAFT POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the exhaust
camshaft position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between exhaust cam-
shaft position sensor connector and engine
ground.
Connector & terminal
(E62) No. 1 (+) — Engine ground (–):
(E65) No. 1 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 146. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
main relay and ex-
haust camshaft po-
sition sensor
connector
Poor contact of
coupling connector
Step Check Yes No
15WRX_STI_US_EN.book 392 ージ 20  
EN(w/o STI)(diag)-393
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
146 CHECK HARNESS BETWEEN ECM AND EX-
HAUST CAMSHAFT POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and exhaust crankshaft position sensor
connector.
Connector & terminal
(E158) No. 32 — (E62) No. 2:
(E158) No. 34 — (E62) No. 3:
(E158) No. 33 — (E65) No. 2:
(E158) No. 34 — (E65) No. 3:
Is the resistance less than 1 Ω? Go to step 147. Repair the open
circuit in the har-
ness between
ECM connector
and exhaust cam-
shaft position sen-
sor connector.
147 CHECK HARNESS BETWEEN ECM AND EX-
HAUST CAMSHAFT POSITION SENSOR.
Measure the resistance between exhaust cam-
shaft position sensor connector and engine
ground.
Connector & terminal
(E62) No. 2 — Engine ground:
(E65) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 148. Repair short cir-
cuit to ground in
the harness
between ECM con-
nector and exhaust
camshaft position
sensor connector.
148 CHECK COMPRESSION PRESSURE.
Check the compression pressure. <Ref. to
ME(w/o STI)-23, INSPECTION, Compres-
sion.>
Is the compression pressure
normal?
Go to step 149. Check the engine.
<Ref. to ME(w/o
STI)-352,
INSPECTION,
Engine Trouble in
General.>
149 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Replace the crankshaft position sensor.
<Ref. to FU(w/o STI)-98, Crankshaft Position
Sensor.>
2) Check that the fault is removed.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Go to step 150.
150 CHECK FOR MALFUNCTION OCCUR-
RENCE.
1) Replace the camshaft position sensor.
<Ref. to FU(w/o STI)-103, Camshaft Position
Sensor.>
2) Check that the fault is removed.
Is the fault removed? Perform the Clear
Memory Mode to
complete. <Ref. to
EN(w/o STI)(diag)-
61, Clear Memory
Mode.>
Check the valve
timing. <Ref. to
ME(w/o STI)-116,
Timing Chain
Assembly.> When
the valve timing is
normal, replace
the ECM. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
Step Check Yes No
15WRX_STI_US_EN.book 393 ージ 20  
EN(w/o STI)(diag)-394
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
EZ:DTC P1C00 BATTERY MONITOR MODULE "A"
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-182, DTC P1C00 BATTERY MONITOR MODULE "A",
Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK DTC.
Check for DTC. <Ref. to EN(w/o STI)(diag)-46,
Read Diagnostic Trouble Code (DTC).>
Is P1C00 displayed in «Present
fault»?
Replace the bat-
tery sensor. <Ref.
to SC(w/o STI)-56,
Battery Sensor.>
Even if DTC is
detected, it has
returned to a nor-
mal condition at
this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
15WRX_STI_US_EN.book 394 ージ 20  
EN(w/o STI)(diag)-395
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FA:DTC P2004 INTAKE MANIFOLD RUNNER CONTROL STUCK OPEN (BANK 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-183, DTC P2004 INTAKE MANIFOLD RUNNER CON-
TROL STUCK OPEN (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK TUMBLE GENERATOR VALVE RH.
1) Remove the tumble generator valve assem-
bly RH.
2) Check the tumble generator valve.
Is there any dirt or clogging with
foreign objects in the tumble
generator valve?
Clean the tumble
generator valve.
Replace the tum-
ble generator valve
RH. <Ref. to FU(w/
o STI)-43, Tumble
Generator Valve
Assembly.>
15WRX_STI_US_EN.book 395 ージ 20  
EN(w/o STI)(diag)-396
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FB:DTC P2005 INTAKE MANIFOLD RUNNER CONTROL STUCK OPEN (BANK 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-184, DTC P2005 INTAKE MANIFOLD RUNNER CON-
TROL STUCK OPEN (BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK TUMBLE GENERATOR VALVE LH.
1) Remove the tumble generator valve assem-
bly LH.
2) Check the tumble generator valve.
Is there any dirt or clogging with
foreign objects in the tumble
generator valve?
Clean the tumble
generator valve.
Replace the tum-
ble generator valve
LH. <Ref. to FU(w/
o STI)-43, Tumble
Generator Valve
Assembly.>
15WRX_STI_US_EN.book 396 ージ 20  
EN(w/o STI)(diag)-397
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FC:DTC P2006 INTAKE MANIFOLD RUNNER CONTROL STUCK CLOSED
(BANK 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-185, DTC P2006 INTAKE MANIFOLD RUNNER CON-
TROL STUCK CLOSED (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK TUMBLE GENERATOR VALVE RH.
1) Remove the tumble generator valve assem-
bly RH.
2) Check the tumble generator valve.
Is there any dirt or clogging with
foreign objects in the tumble
generator valve?
Clean the tumble
generator valve.
Replace the tum-
ble generator valve
RH. <Ref. to FU(w/
o STI)-43, Tumble
Generator Valve
Assembly.>
15WRX_STI_US_EN.book 397 ージ 20  
EN(w/o STI)(diag)-398
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FD:DTC P2007 INTAKE MANIFOLD RUNNER CONTROL STUCK CLOSED
(BANK 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-186, DTC P2007 INTAKE MANIFOLD RUNNER CON-
TROL STUCK CLOSED (BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK TUMBLE GENERATOR VALVE LH.
1) Remove the tumble generator valve assem-
bly LH.
2) Check the tumble generator valve.
Is there any dirt or clogging with
foreign objects in the tumble
generator valve?
Clean the tumble
generator valve.
Replace the tum-
ble generator valve
LH. <Ref. to FU(w/
o STI)-43, Tumble
Generator Valve
Assembly.>
15WRX_STI_US_EN.book 398 ージ 20  
EN(w/o STI)(diag)-399
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FE:DTC P2009 INTAKE MANIFOLD RUNNER CONTROL CIRCUIT LOW (BANK 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-187, DTC P2009 INTAKE MANIFOLD RUNNER CON-
TROL CIRCUIT LOW (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
RH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 14 (+) — Engine ground (–):
(E159) No. 30 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
harness between
ECM connector
and tumble gener-
ator valve actuator
RH connector.
Replace the tum-
ble generator valve
actuator RH. <Ref.
to FU(w/o STI)-45,
Tumble Generator
Valve Actuator.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
E51
E55
45
213
E55
1B40
EN-10339
2C27
3C19
4C14
5C30
E51
1B41
2
3
4C22
5C6
E158B:
E159C:
ECM
TUMBLE GENERATOR
VALVE ACTUATOR LH
TUMBLE GENERATOR
VALVE ACTUATOR RH
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 399 ージ 20  
EN(w/o STI)(diag)-400
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FF:DTC P2012 INTAKE MANIFOLD RUNNER CONTROL CIRCUIT LOW (BANK 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-188, DTC P2012 INTAKE MANIFOLD RUNNER CON-
TROL CIRCUIT LOW (BANK 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
LH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(E159) No. 6 (+) — Engine ground (–):
(E159) No. 22 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
harness between
ECM connector
and tumble gener-
ator valve actuator
LH connector.
Replace the tum-
ble generator valve
actuator LH. <Ref.
to FU(w/o STI)-45,
Tumble Generator
Valve Actuator.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
E51
E55
45
213
E55
1B40
EN-10339
2C27
3C19
4C14
5C30
E51
1B41
2
3
4C22
5C6
E158B:
E159C:
ECM
TUMBLE GENERATOR
VALVE ACTUATOR LH
TUMBLE GENERATOR
VALVE ACTUATOR RH
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 400 ージ 20  
EN(w/o STI)(diag)-401
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FG:DTC P2016 TUMBLE GENERATED VALVE POSITION SENSOR 1 CIRCUIT
LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-189, DTC P2016 TUMBLE GENERATED VALVE POSI-
TION SENSOR 1 CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
E51
E55
45
213
E55
1B40
EN-10339
2C27
3C19
4C14
5C30
E51
1B41
2
3
4C22
5C6
E158B:
E159C:
ECM
TUMBLE GENERATOR
VALVE ACTUATOR LH
TUMBLE GENERATOR
VALVE ACTUATOR RH
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 401 ージ 20  
EN(w/o STI)(diag)-402
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «TGV Position Sensor R»
using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «TGV Position
Sensor R» less than 0.2 V?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK POWER SUPPLY OF TUMBLE GEN-
ERATOR VALVE ACTUATOR RH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from tumble gen-
erator valve actuator RH.
3) Turn the ignition switch to ON.
4) Measure the voltage between tumble gener-
ator valve actuator RH connector and engine
ground.
Connector & terminal
(E55) No. 3 (+) — Engine ground (–):
Is the voltage 4.5 V or more? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and tumble gener-
ator valve actuator
RH connector
Poor contact of
ECM connector
3 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
RH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and tumble generator valve
actuator RH connector.
Connector & terminal
(E158) No. 40 — (E55) No. 1:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit in harness
between ECM con-
nector and tumble
generator valve
actuator RH con-
nector.
4 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
RH CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 40 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and tumble gener-
ator valve actuator
RH connector.
5 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and tumble gen-
erator valve actuator RH connector.
Is there poor contact of ECM or
the tumble generator valve
actuator RH connector?
Repair the poor
contact of ECM or
tumble generator
valve actuator RH
connector.
Replace the tum-
ble generator valve
actuator RH. <Ref.
to FU(w/o STI)-43,
Tumble Generator
Valve Assembly.>
15WRX_STI_US_EN.book 402 ージ 20  
EN(w/o STI)(diag)-403
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FH:DTC P2017 TUMBLE GENERATED VALVE POSITION SENSOR 1 CIRCUIT
HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-190, DTC P2017 TUMBLE GENERATED VALVE POSI-
TION SENSOR 1 CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
E51
E55
45
213
E55
1B40
EN-10339
2C27
3C19
4C14
5C30
E51
1B41
2
3
4C22
5C6
E158B:
E159C:
ECM
TUMBLE GENERATOR
VALVE ACTUATOR LH
TUMBLE GENERATOR
VALVE ACTUATOR RH
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 403 ージ 20  
EN(w/o STI)(diag)-404
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «TGV Position Sensor R»
using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «TGV Position
Sensor R» 5 V or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
RH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from tumble gen-
erator valve actuator RH.
3) Start the engine.
4) Read the value of «TGV Position Sensor R»
using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «TGV Position
Sensor R» 5 V or more?
Repair the short
circuit to power in
harness between
ECM connector
and tumble gener-
ator valve actuator
RH connector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
RH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between
tumble generator valve actuator RH connector
and engine ground.
Connector & terminal
(E55) No. 2 — Engine ground:
Is the resistance less than 5 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and tumble gener-
ator valve actuator
RH connector
Poor contact of
ECM connector
4 CHECK FOR POOR CONTACT.
Check for poor contact of tumble generator
valve actuator RH connector.
Is there poor contact of the tum-
ble generator valve actuator RH
connector?
Repair the poor
contact of tumble
generator valve
actuator RH con-
nector.
Replace the tum-
ble generator valve
actuator RH. <Ref.
to FU(w/o STI)-43,
Tumble Generator
Valve Assembly.>
15WRX_STI_US_EN.book 404 ージ 20  
EN(w/o STI)(diag)-405
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FI: DTC P2021 TUMBLE GENERATED VALVE POSITION SENSOR 2 CIRCUIT
LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-191, DTC P2021 TUMBLE GENERATED VALVE POSI-
TION SENSOR 2 CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
E51
E55
45
213
E55
1B40
EN-10339
2C27
3C19
4C14
5C30
E51
1B41
2
3
4C22
5C6
E158B:
E159C:
ECM
TUMBLE GENERATOR
VALVE ACTUATOR LH
TUMBLE GENERATOR
VALVE ACTUATOR RH
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 405 ージ 20  
EN(w/o STI)(diag)-406
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «TGV Position Sensor L»
using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «TGV Position
Sensor L» less than 0.2 V?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK POWER SUPPLY OF TUMBLE GEN-
ERATOR VALVE ACTUATOR LH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from tumble gen-
erator valve actuator LH.
3) Turn the ignition switch to ON.
4) Measure the voltage between tumble gener-
ator valve actuator LH connector and engine
ground.
Connector & terminal
(E51) No. 3 (+) — Engine ground (–):
Is the voltage 4.5 V or more? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and tumble gener-
ator valve actuator
LH connector
Poor contact of
ECM connector
3 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
LH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and tumble generator valve
actuator LH connector.
Connector & terminal
(E158) No. 41 — (E51) No. 1:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit in harness
between ECM con-
nector and tumble
generator valve
actuator LH con-
nector.
4 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
LH CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 41 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and tumble gener-
ator valve actuator
LH connector.
5 CHECK FOR POOR CONTACT.
Check for poor contact of ECM and tumble gen-
erator valve actuator LH connector.
Is there poor contact of ECM or
the tumble generator valve
actuator LH connector?
Repair the poor
contact of ECM or
tumble generator
valve actuator LH
connector.
Replace the tum-
ble generator valve
actuator LH. <Ref.
to FU(w/o STI)-43,
Tumble Generator
Valve Assembly.>
15WRX_STI_US_EN.book 406 ージ 20  
EN(w/o STI)(diag)-407
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FJ:DTC P2022 TUMBLE GENERATED VALVE POSITION SENSOR 2 CIRCUIT
HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-192, DTC P2022 TUMBLE GENERATED VALVE POSI-
TION SENSOR 2 CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Engine stalls.
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
E51
E55
45
213
E55
1B40
EN-10339
2C27
3C19
4C14
5C30
E51
1B41
2
3
4C22
5C6
E158B:
E159C:
ECM
TUMBLE GENERATOR
VALVE ACTUATOR LH
TUMBLE GENERATOR
VALVE ACTUATOR RH
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 407 ージ 20  
EN(w/o STI)(diag)-408
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the value of «TGV Position Sensor L»
using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «TGV Position
Sensor L» 5 V or more?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
2 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
LH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from tumble gen-
erator valve actuator LH.
3) Start the engine.
4) Read the value of «TGV Position Sensor L»
using the Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «TGV Position
Sensor L» 5 V or more?
Repair the short
circuit to power in
harness between
ECM connector
and tumble gener-
ator valve actuator
LH connector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE ACTUATOR
LH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between
tumble generator valve actuator LH connector
and engine ground.
Connector & terminal
(E51) No. 2 — Engine ground:
Is the resistance less than 5 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and tumble gener-
ator valve actuator
LH connector
Poor contact of
ECM connector
4 CHECK FOR POOR CONTACT.
Check for poor contact of tumble generator
valve actuator LH connector.
Is there poor contact of the tum-
ble generator valve actuator LH
connector?
Repair the poor
contact of tumble
generator valve
actuator LH con-
nector.
Replace the tum-
ble generator valve
actuator LH. <Ref.
to FU(w/o STI)-43,
Tumble Generator
Valve Assembly.>
15WRX_STI_US_EN.book 408 ージ 20  
EN(w/o STI)(diag)-409
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FK:DTC P2096 POST CATALYST FUEL TRIM SYSTEM TOO LEAN (BANK 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-193, DTC P2096 POST CATALYST FUEL TRIM SYS-
TEM TOO LEAN (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 409 ージ 20  
EN(w/o STI)(diag)-410
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 410 ージ 20  
EN(w/o STI)(diag)-411
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(w/o STI)(diag)-
85, List of Diagnos-
tic Trouble Code
(DTC).>
Go to step 2.
2 CHECK FRONT OXYGEN (A/F) SENSOR
CONNECTOR AND COUPLING CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 3.
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 411 ージ 20  
EN(w/o STI)(diag)-412
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
3 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
front oxygen (A/F) sensor.
3) Measure the resistance of harness between
ECM connector and front oxygen (A/F) sensor
connector.
Connector & terminal
(E158) No. 15 — (E24) No. 1:
(E158) No. 27 — (E24) No. 4:
(E158) No. 39 — (E24) No. 5:
Is the resistance less than 1 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector
Poor contact of
coupling connector
4 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B158) No. 15 — Chassis ground:
(B158) No. 27 — Chassis ground:
(B158) No. 39 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector.
5 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between front oxygen
(A/F) sensor connector and chassis ground.
Connector & terminal
(E24) No. 1 (+) — Chassis ground (–):
(E24) No. 4 (+) — Chassis ground (–):
(E24) No. 5 (+) — Chassis ground (–):
Is the voltage 8 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
Go to step 6.
6 CHECK EXHAUST SYSTEM. Are there holes or loose bolts
on exhaust system?
Repair the exhaust
system.
Go to step 7.
7 CHECK AIR INTAKE SYSTEM. Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
Go to step 8.
8 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
1) Connect the front oxygen (A/F) sensor con-
nector.
2) Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 328 —
358 kPa (3.3 — 3.7 kgf/cm
2
, 48
— 52 psi)?
Go to step 9. Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
Step Check Yes No
15WRX_STI_US_EN.book 412 ージ 20  
EN(w/o STI)(diag)-413
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
9 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm up completely.
2) Read the value of «Coolant Temp.» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Coolant Temp
75°C (167°F) or more?
Go to step 10. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
10 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Read the value of «Mass Air Flow» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value in «Mass Air
Flow» 2.0 — 5.0 g/s (0.26 —
0.66 lb/s)?
Go to step 11. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 413 ージ 20  
EN(w/o STI)(diag)-414
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
11 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Open the front hood.
6) Measure the ambient temperature.
7) Read the value of «IAT Sensor #11» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Subtract ambient temperature
value from the value of «IAT
Sensor #11». Is the obtained
value –10 — 50°C (–18 —
90°F)?
Go to step 12. Check the mass air
flow and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-118, Mass
Air Flow and Intake
Air Temperature
Sensor.>
12 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
keep the engine speed at 3,000 rpm. (2 minutes
maximum)
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» 0.490 V or more?
Go to step 13. Go to step 14.
13 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
rapidly reduce the engine speed from 3,000
rpm.
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» 0.250 V or more?
Go to step 15. Go to step 14.
Step Check Yes No
15WRX_STI_US_EN.book 414 ージ 20  
EN(w/o STI)(diag)-415
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
14 CHECK REAR OXYGEN SENSOR CONNEC-
TOR AND COUPLING CONNECTOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 16.
15 CHECK FRONT OXYGEN (A/F) SENSOR US-
ING REAR OXYGEN SENSOR SIGNAL.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), then
keep the engine idling for 5 minutes or more.
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» kept at 0.250 V or less for
5 minutes or more?
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
Go to step 16.
16 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 42 — (E25) No. 3:
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 17. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and rear oxygen
sensor connector
Poor contact of
coupling connector
17 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between rear oxygen
sensor connector and chassis ground.
Connector & terminal
(E25) No. 4 (+) — Chassis ground (–):
Is the voltage 0.2 — 0.5 V? Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and rear oxygen
sensor connector
Poor contact of
ECM connector
Poor contact of
coupling connector
Step Check Yes No
15WRX_STI_US_EN.book 415 ージ 20  
EN(w/o STI)(diag)-416
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FL:DTC P2097 POST CATALYST FUEL TRIM SYSTEM TOO RICH (BANK 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-194, DTC P2097 POST CATALYST FUEL TRIM SYS-
TEM TOO RICH (BANK 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 416 ージ 20  
EN(w/o STI)(diag)-417
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 417 ージ 20  
EN(w/o STI)(diag)-418
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(w/o STI)(diag)-
85, List of Diagnos-
tic Trouble Code
(DTC).>
Go to step 2.
2 CHECK FRONT OXYGEN (A/F) SENSOR
CONNECTOR AND COUPLING CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 3.
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 418 ージ 20  
EN(w/o STI)(diag)-419
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
3 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
front oxygen (A/F) sensor.
3) Measure the resistance of harness between
ECM connector and front oxygen (A/F) sensor
connector.
Connector & terminal
(E158) No. 15 — (E24) No. 1:
(E158) No. 27 — (E24) No. 4:
(E158) No. 39 — (E24) No. 5:
Is the resistance less than 1 Ω? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector
Poor contact of
coupling connector
4 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(E158) No. 15 — Chassis ground:
(E158) No. 27 — Chassis ground:
(E158) No. 39 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector.
5 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between front oxygen
(A/F) sensor connector and chassis ground.
Connector & terminal
(E24) No. 1 (+) — Chassis ground (–):
(E24) No. 4 (+) — Chassis ground (–):
(E24) No. 5 (+) — Chassis ground (–):
Is the voltage 8 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
Go to step 6.
6 CHECK EXHAUST SYSTEM. Are there holes or loose bolts
on exhaust system?
Repair the exhaust
system.
Go to step 7.
7 CHECK AIR INTAKE SYSTEM. Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
Go to step 8.
8 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
1) Connect the front oxygen (A/F) sensor con-
nector.
2) Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 328 —
358 kPa (3.3 — 3.7 kgf/cm
2
, 48
— 52 psi)?
Go to step 9. Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
Step Check Yes No
15WRX_STI_US_EN.book 419 ージ 20  
EN(w/o STI)(diag)-420
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
9 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm up completely.
2) Read the value of «Coolant Temp.» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Coolant Temp
75°C (167°F) or more?
Go to step 10. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
10 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Read the value of «Mass Air Flow» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value in «Mass Air
Flow» 2.0 — 5.0 g/s (0.26 —
0.66 lb/s)?
Go to step 11. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 420 ージ 20  
EN(w/o STI)(diag)-421
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
11 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Open the front hood.
6) Measure the ambient temperature.
7) Read the value of «IAT Sensor #11» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Subtract ambient temperature
value from the value of «IAT
Sensor #11». Is the obtained
value –10 — 50°C (–18 —
90°F)?
Go to step 12. Check the mass air
flow and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-118, Mass
Air Flow and Intake
Air Temperature
Sensor.>
12 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
keep the engine speed at 3,000 rpm. (2 minutes
maximum)
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» 0.490 V or more?
Go to step 13. Go to step 14.
13 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
rapidly reduce the engine speed from 3,000
rpm.
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» 0.250 V or less?
Go to step 15. Go to step 14.
Step Check Yes No
15WRX_STI_US_EN.book 421 ージ 20  
EN(w/o STI)(diag)-422
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
14 CHECK REAR OXYGEN SENSOR CONNEC-
TOR AND COUPLING CONNECTOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 16.
15 CHECK FRONT OXYGEN (A/F) SENSOR US-
ING REAR OXYGEN SENSOR SIGNAL.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), then
keep the engine idling for 5 minutes or more.
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» kept at 0.8 V or more for 5
minutes or more?
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
Go to step 16.
16 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 42 — (E25) No. 3:
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 17. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and rear oxygen
sensor connector
Poor contact of
coupling connector
17 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between rear oxygen
sensor connector and chassis ground.
Connector & terminal
(E25) No. 4 (+) — Chassis ground (–):
Is the voltage 0.2 — 0.5 V? Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and rear oxygen
sensor connector
Poor contact of
ECM connector
Poor contact of
coupling connector
Step Check Yes No
15WRX_STI_US_EN.book 422 ージ 20  
EN(w/o STI)(diag)-423
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FM:DTC P2101 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT RANGE/
PERFORMANCE
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-195, DTC P2101 THROTTLE ACTUATOR CONTROL
MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
Engine stalls.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 423 ージ 20  
EN(w/o STI)(diag)-424
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to terminals No. 16 and
No. 17 of electronic throttle control relay.
4) Measure the resistance between electronic
throttle control relay terminals.
Terminals
No. 14 — No. 15:
Is the resistance less than 1 Ω? Go to step 2. Replace the elec-
tronic throttle con-
trol relay. <Ref. to
FU(w/o STI)-139,
Electronic Throttle
Control Relay.>
ECM
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B225
14
17
15
16
B550
215
317
B220
1011
E57
B17
B29
B18
B30
6
5
3
2
4
1
C1
C2
A39
A11
B225B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10800
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
BATTERY
ELECTRONIC
THROTTLE
CONTROL
MAIN RELAY
FUSE HOLDER
ELECTRONIC
THROTTLE CONTROL
RELAY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 424 ージ 20  
EN(w/o STI)(diag)-425
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
Measure the voltage between electronic throttle
control relay connector and chassis ground.
Connector & terminal
(B225) No. 15 (+) — Chassis ground (–):
Is the voltage 10 V or more? Go to step 3. Repair the open or
ground short circuit
of power supply
circuit.
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Disconnect the connector from ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B225) No. 17 (+) — Chassis ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B225) No. 14 — Chassis ground:
(B225) No. 17 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and electronic
throttle control
relay connector.
5 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
Measure the resistance between ECM connec-
tor and electronic throttle control relay connec-
tor.
Connector & terminal
(B134) No. 39 — (B225) No. 17:
(B134) No. 11 — (B225) No. 14:
Is the resistance less than 1 Ω? Go to step 6. Repair the open
circuit in harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.
6 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from electronic
throttle control.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 18 — Engine ground:
(E158) No. 17 — Engine ground:
(E158) No. 29 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 7. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
7 CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 1 — Engine ground:
(E57) No. 4 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 8. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
Replace the ECM if
defective. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
Step Check Yes No
15WRX_STI_US_EN.book 425 ージ 20  
EN(w/o STI)(diag)-426
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
8 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness between
ECM connector and electronic throttle control
connector.
Connector & terminal
(E158) No. 17 — (E57) No. 1:
(E158) No. 30 — (E57) No. 3:
(E158) No. 29 — (E57) No. 4:
Is the resistance less than 1 Ω? Go to step 9. Repair the open
circuit of harness
between ECM con-
nector and elec-
tronic throttle
control connector.
9 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 3 — Engine ground:
Is the resistance less than 5 Ω? Go to step 10. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
ECM connector
Poor contact of
coupling connector
10 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 1 (+) — Engine ground (–):
(E57) No. 4 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Go to step 11.
11 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(E158) No. 18 — (E158) No. 17:
(E158) No. 18 — (E158) No. 29:
Is the resistance 1 MΩ or
more?
Go to step 12. Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
12 CHECK SENSOR OUTPUT.
1) Connect all connectors.
2) Start the engine and warm up completely.
3) Stop the engine, and then turn the ignition
switch to ON (engine OFF).
4) Read the value of «Main-Throttle Sensor»
using Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «Main-Throttle
Sensor» 0.60 — 0.65 V?
Go to step 13. Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to FU(w/o
STI)-15, Throttle
Body.>
Step Check Yes No
15WRX_STI_US_EN.book 426 ージ 20  
EN(w/o STI)(diag)-427
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
13 CHECK SENSOR OUTPUT.
Read the value of «Sub-Throttle Sensor» using
Subaru Select Monitor.
NOTE:
For detailed operation procedures, refer to
“Current Data Display For Engine”. <Ref. to
EN(w/o STI)(diag)-37, Subaru Select Monitor.>
Is the value of «Sub-Throttle
Sensor» 0.60 — 0.65 V?
Go to step 14. Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to FU(w/o
STI)-15, Throttle
Body.>
14 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance between ECM con-
nector and electronic throttle control connector.
Connector & terminal
(E159) No. 1 — (E57) No. 5:
(E159) No. 2 — (E57) No. 6:
Is the resistance less than 1 Ω? Go to step 15. Repair the open
circuit of harness
between ECM con-
nector and elec-
tronic throttle
control.
15 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 5 (+) — Engine ground (–):
(E57) No. 6 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Go to step 16.
16 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 5 — Engine ground:
(E57) No. 6 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 17. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
17 CHECK ELECTRONIC THROTTLE CON-
TROL MOTOR HARNESS.
Measure the resistance between electronic
throttle control connectors.
Connector & terminal
(E57) No. 5 — (E57) No. 6:
Is the resistance 1 MΩ or
more?
Go to step 18. Repair the short
circuit in harness
between ECM con-
nector and elec-
tronic throttle
control connector.
18 CHECK ELECTRONIC THROTTLE CON-
TROL GROUND CIRCUIT.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(B134) No. 35 — Engine ground:
(B134) No. 47 — Engine ground:
(E159) No. 10 — Engine ground:
(E159) No. 17 — Engine ground:
(E159) No. 18 — Engine ground:
(E159) No. 25 — Engine ground:
(E159) No. 26 — Engine ground:
Is the resistance less than 5 Ω? Go to step 19. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
coupling connector
Step Check Yes No
15WRX_STI_US_EN.book 427 ージ 20  
EN(w/o STI)(diag)-428
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
19 CHECK ELECTRONIC THROTTLE CON-
TROL.
Measure the resistance between electronic
throttle control terminals.
Terminals
No. 5 — No. 6:
Is the resistance 50 Ω or less? Go to step 20. Replace the elec-
tronic throttle con-
trol. <Ref. to FU(w/
o STI)-15, Throttle
Body.>
20 CHECK ELECTRONIC THROTTLE CON-
TROL.
Move the throttle valve to the fully open and fully
closed positions with fingers.
Check that the valve returns to the specified
position when releasing fingers.
Does the valve return to the
specified position? Standard
value: 3 mm (0.12 in) from fully
closed position
Repair the poor
contact of ECM
connector.
Replace the elec-
tronic throttle con-
trol. <Ref. to FU(w/
o STI)-15, Throttle
Body.>
Step Check Yes No
15WRX_STI_US_EN.book 428 ージ 20  
EN(w/o STI)(diag)-429
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FN:DTC P2102 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-196, DTC P2102 THROTTLE ACTUATOR CONTROL
MOTOR CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
Engine stalls.
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
ECM
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B225
14
17
15
16
B550
215
317
B220
1011
E57
B17
B29
B18
B30
6
5
3
2
4
1
C1
C2
A39
A11
B225B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10800
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
BATTERY
ELECTRONIC
THROTTLE
CONTROL
MAIN RELAY
FUSE HOLDER
ELECTRONIC
THROTTLE CONTROL
RELAY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 429 ージ 20  
EN(w/o STI)(diag)-430
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to terminals No. 16 and
No. 17 of electronic throttle control relay.
4) Measure the resistance between electronic
throttle control relay terminals.
Terminals
No. 14 — No. 15:
Is the resistance less than 1 Ω? Go to step 2. Replace the elec-
tronic throttle con-
trol relay. <Ref. to
FU(w/o STI)-139,
Electronic Throttle
Control Relay.>
2 CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
Measure the voltage between electronic throttle
control relay connector and chassis ground.
Connector & terminal
(B225) No. 15 (+) — Chassis ground (–):
Is the voltage 10 V or more? Go to step 3. Repair the open or
ground short circuit
of power supply
circuit.
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Disconnect the connector from ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B225) No. 17 (+) — Chassis ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B225) No. 14 — Chassis ground:
(B225) No. 17 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and electronic
throttle control
relay connector.
5 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
Measure the resistance between ECM connec-
tor and electronic throttle control relay connec-
tor.
Connector & terminal
(B135) No. 39 — (B225) No. 17:
(B135) No. 11 — (B225) No. 14:
Is the resistance less than 1 Ω? Repair the poor
contact of ECM
connector.
Repair the open
circuit in harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.
15WRX_STI_US_EN.book 430 ージ 20  
EN(w/o STI)(diag)-431
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FO:DTC P2103 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-198, DTC P2103 THROTTLE ACTUATOR CONTROL
MOTOR CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
ECM
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B225
14
17
15
16
B550
215
317
B220
1011
E57
B17
B29
B18
B30
6
5
3
2
4
1
C1
C2
A39
A11
B225B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10800
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
BATTERY
ELECTRONIC
THROTTLE
CONTROL
MAIN RELAY
FUSE HOLDER
ELECTRONIC
THROTTLE CONTROL
RELAY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 431 ージ 20  
EN(w/o STI)(diag)-432
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FP:DTC P2109 THROTTLE/PEDAL POSITION SENSOR “A” MINIMUM STOP
PERFORMANCE
NOTE:
For the diagnostic procedure, refer to DTC P2101. <Ref. to EN(w/o STI)(diag)-423, DTC P2101 THROTTLE
ACTUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Procedure with Diagnos-
tic Trouble Code (DTC).>
FQ:DTC P2119 THROTTLE ACTUATOR CONTROL THROTTLE BODY RANGE/
PERFORMANCE
NOTE:
For the diagnostic procedure, refer to DTC P2101. <Ref. to EN(w/o STI)(diag)-423, DTC P2101 THROTTLE
ACTUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Procedure with Diagnos-
tic Trouble Code (DTC).>
Step Check Yes No
1 CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Measure the resistance between electronic
throttle control relay terminals.
Terminals
No. 14 — No. 15:
Is the resistance 1 MΩ or
more?
Go to step 2. Replace the elec-
tronic throttle con-
trol relay. <Ref. to
FU(w/o STI)-139,
Electronic Throttle
Control Relay.>
2 CHECK SHORT CIRCUIT OF ELECTRONIC
THROTTLE CONTROL RELAY POWER SUP-
PLY.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B225) No. 14 (+) — Chassis ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.
Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(B134) No. 39 — Engine ground:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of ECM
connector.
Repair the short
circuit to ground in
harness between
ECM connector
and electronic
throttle control
relay connector.
15WRX_STI_US_EN.book 432 ージ 20  
EN(w/o STI)(diag)-433
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FR:DTC P2122 THROTTLE/PEDAL POSITION SENSOR/SWITCH “D” CIRCUIT
LOW INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-202, DTC P2122 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “D” CIRCUIT LOW INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
56341
2
B315
1
3
5
2
4
6
B134A:
E159C:
B315
*
A17
A31
A30
A29
A19
A18
EN-10812
*
B122
J/C
*
*
78
5
6
34
2
1
B122
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
ECM
: TERMINAL No. OPTIONAL ARRANGEMENT
ACCELERATOR PEDAL
POSITION SENSOR
(BROWN)
(GRAY)
15WRX_STI_US_EN.book 433 ージ 20  
EN(w/o STI)(diag)-434
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
accelerator pedal position sensor.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(B134) No. 30 — Engine ground:
(B134) No. 17 — Engine ground:
(B134) No. 17 — (B134) No. 19:
Is the resistance 1 MΩ or
more?
Go to step 2. Repair the short
circuit to ground in
harness between
ECM connector
and accelerator
pedal position sen-
sor connector.
2 CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between accelera-
tor pedal position sensor connector and chassis
ground.
Connector & terminal
(B315) No. 6 — Chassis ground:
Is the resistance 1 MΩ or
more?
Replace the accel-
erator pedal. <Ref.
to SP(w/o STI)-4,
Accelerator
Pedal.>
Repair the short
circuit to ground in
harness between
ECM connector
and accelerator
pedal position sen-
sor connector.
Replace the ECM if
defective. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
15WRX_STI_US_EN.book 434 ージ 20  
EN(w/o STI)(diag)-435
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FS:DTC P2123 THROTTLE/PEDAL POSITION SENSOR/SWITCH “D” CIRCUIT
HIGH INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-203, DTC P2123 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “D” CIRCUIT HIGH INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
56341
2
B315
1
3
5
2
4
6
B134A:
E159C:
B315
*
A17
A31
A30
A29
A19
A18
EN-10812
*
B122
J/C
*
*
78
5
6
34
2
1
B122
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
ECM
: TERMINAL No. OPTIONAL ARRANGEMENT
ACCELERATOR PEDAL
POSITION SENSOR
(BROWN)
(GRAY)
15WRX_STI_US_EN.book 435 ージ 20  
EN(w/o STI)(diag)-436
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
accelerator pedal position sensor.
3) Measure the resistance of harness between
ECM connector and accelerator pedal position
sensor connector.
Connector & terminal
(B134) No. 17 — (B315) No. 6:
(B134) No. 31 — (B315) No. 5:
Is the resistance less than 1 Ω? Go to step 2. Repair the open
circuit of harness
between ECM con-
nector and accel-
erator pedal
position sensor
connector.
2 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Connect the connector to ECM.
2) Measure the resistance between accelera-
tor pedal position sensor connector and chassis
ground.
Connector & terminal
(B315) No. 5 — Chassis ground:
Is the resistance less than 5 Ω? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
ECM connector
Poor contact of
coupling connector
3 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between accelerator
pedal position sensor connector and chassis
ground.
Connector & terminal
(B315) No. 6 (+) — Chassis ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power
supply in harness
between ECM con-
nector and accel-
erator pedal
position sensor
connector.
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(B134) No. 17 — (B134) No. 30:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of acceler-
ator pedal position
sensor connector.
Replace the accel-
erator pedal if
defective. <Ref. to
SP(w/o STI)-4,
Accelerator
Pedal.>
Repair the short
circuit to power
supply in harness
between ECM con-
nector and accel-
erator pedal
position sensor
connector.
15WRX_STI_US_EN.book 436 ージ 20  
EN(w/o STI)(diag)-437
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FT:DTC P2127 THROTTLE/PEDAL POSITION SENSOR/SWITCH “E” CIRCUIT
LOW INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-204, DTC P2127 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “E” CIRCUIT LOW INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
56341
2
B315
1
3
5
2
4
6
B134A:
E159C:
B315
*
A17
A31
A30
A29
A19
A18
EN-10812
*
B122
J/C
*
*
78
5
6
34
2
1
B122
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
ECM
: TERMINAL No. OPTIONAL ARRANGEMENT
ACCELERATOR PEDAL
POSITION SENSOR
(BROWN)
(GRAY)
15WRX_STI_US_EN.book 437 ージ 20  
EN(w/o STI)(diag)-438
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
accelerator pedal position sensor.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(B134) No. 18 — Engine ground:
(B134) No. 29 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 2. Repair the short
circuit to ground in
harness between
ECM connector
and accelerator
pedal position sen-
sor connector.
2 CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between accelera-
tor pedal position sensor connector and chassis
ground.
Connector & terminal
(B315) No. 3 — Chassis ground:
Is the resistance 1 MΩ or
more?
Replace the accel-
erator pedal. <Ref.
to SP(w/o STI)-4,
Accelerator
Pedal.>
Repair the short
circuit to ground in
harness between
ECM connector
and accelerator
pedal position sen-
sor connector.
Replace the ECM if
defective. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
15WRX_STI_US_EN.book 438 ージ 20  
EN(w/o STI)(diag)-439
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FU:DTC P2128 THROTTLE/PEDAL POSITION SENSOR/SWITCH “E” CIRCUIT
HIGH INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-205, DTC P2128 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “E” CIRCUIT HIGH INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
56341
2
B315
1
3
5
2
4
6
B134A:
E159C:
B315
*
A17
A31
A30
A29
A19
A18
EN-10812
*
B122
J/C
*
*
78
5
6
34
2
1
B122
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
ECM
: TERMINAL No. OPTIONAL ARRANGEMENT
ACCELERATOR PEDAL
POSITION SENSOR
(BROWN)
(GRAY)
15WRX_STI_US_EN.book 439 ージ 20  
EN(w/o STI)(diag)-440
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
accelerator pedal position sensor.
3) Measure the resistance of harness between
ECM connector and accelerator pedal position
sensor connector.
Connector & terminal
(B134) No. 29 — (B315) No. 3:
(B134) No. 19 — (B315) No. 2:
Is the resistance less than 1 Ω? Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and accelerator
pedal position sen-
sor connector
Poor contact of
joint connector
2 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Connect the connector to ECM.
2) Measure the resistance between accelera-
tor pedal position sensor connector and chassis
ground.
Connector & terminal
(B315) No. 2 — Chassis ground:
Is the resistance less than 1 Ω? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
ECM connector
Poor contact of
coupling connector
3 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between accelerator
pedal position sensor connector and chassis
ground.
Connector & terminal
(B315) No. 3 (+) — Chassis ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power
supply in harness
between ECM con-
nector and accel-
erator pedal
position sensor
connector.
Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(B134) No. 18 — (B134) No. 29:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of acceler-
ator pedal position
sensor connector.
Replace the accel-
erator pedal if
defective. <Ref. to
SP(w/o STI)-4,
Accelerator
Pedal.>
Repair the short
circuit to power
supply in harness
between ECM con-
nector and accel-
erator pedal
position sensor
connector.
15WRX_STI_US_EN.book 440 ージ 20  
EN(w/o STI)(diag)-441
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FV:DTC P2135 THROTTLE/PEDAL POSITION SENSOR/SWITCH “A”/“B” VOLT-
AGE CORRELATION
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-206, DTC P2135 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “A”/“B” VOLTAGE CORRELATION, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
ECM
E158B:
B134A:
E159C:
7
9
10
8
5
23
11 12
6
19 21 222017
24
35 36
47 48
18
31
33
34
32
29 30
43 45 464441 42
3
4
12
15 1613 14
27
28
25 26
39 4037 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
123456
E57
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B22
12
3
4
5678
9
10 11 12
1413 15 16
B225
14
17
15
16
B550
215
317
B220
1011
E57
B17
B29
B18
B30
6
5
3
2
4
1
C1
C2
A39
A11
B225B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10800
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
SBF-7
BATTERY
ELECTRONIC
THROTTLE
CONTROL
MAIN RELAY
FUSE HOLDER
ELECTRONIC
THROTTLE CONTROL
RELAY
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 441 ージ 20  
EN(w/o STI)(diag)-442
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance between the ECM
connector and engine ground.
Connector & terminal
(E158) No. 18 — Engine ground:
(E158) No. 17 — Engine ground:
(E158) No. 29 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 2. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
2 CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 1 — Engine ground:
(E57) No. 4 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 3. Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
Replace the ECM if
defective. <Ref. to
FU(w/o STI)-132,
Engine Control
Module (ECM).>
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness between
ECM connector and electronic throttle control
connector.
Connector & terminal
(E158) No. 17 — (E57) No. 1:
(E158) No. 30 — (E57) No. 3:
(E158) No. 29 — (E57) No. 4:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit of harness
between ECM con-
nector and elec-
tronic throttle
control connector.
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 3 — Engine ground:
Is the resistance less than 5 Ω? Go to step 5. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
ECM connector
Poor contact of
coupling connector
5 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 1 (+) — Engine ground (–):
(E57) No. 4 (+) — Engine ground (–):
Is the voltage 5 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Go to step 6.
15WRX_STI_US_EN.book 442 ージ 20  
EN(w/o STI)(diag)-443
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(E158) No. 18 — (E158) No. 17:
(E158) No. 18 — (E158) No. 29:
Is the resistance 1 MΩ or
more?
Repair the poor
contact of elec-
tronic throttle con-
trol connector.
Replace the elec-
tronic throttle con-
trol if defective.
<Ref. to FU(w/o
STI)-15, Throttle
Body.>
Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.
Step Check Yes No
15WRX_STI_US_EN.book 443 ージ 20  
EN(w/o STI)(diag)-444
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FW:DTC P2138 THROTTLE/PEDAL POSITION SENSOR/SWITCH “D”/“E” VOLT-
AGE CORRELATION
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-207, DTC P2138 THROTTLE/PEDAL POSITION SEN-
SOR/SWITCH “D”/“E” VOLTAGE CORRELATION, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
56341
2
B315
1
3
5
2
4
6
B134A:
E159C:
B315
*
A17
A31
A30
A29
A19
A18
EN-10812
*
B122
J/C
*
*
78
5
6
34
2
1
B122
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
ECM
: TERMINAL No. OPTIONAL ARRANGEMENT
ACCELERATOR PEDAL
POSITION SENSOR
(BROWN)
(GRAY)
15WRX_STI_US_EN.book 444 ージ 20  
EN(w/o STI)(diag)-445
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK ACCELERATOR PEDAL POSITION
SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
Main accelerator pedal position sensor
signal
(B134) No. 17 (+) — Engine ground (–):
Sub accelerator pedal position sensor
signal
(B134) No. 29 (+) — Engine ground (–):
Is the difference in measured
values for the main accelerator
pedal position sensor signal
and the sub accelerator pedal
position sensor signal 0 V?
Go to step 3. Go to step 2.
2 CHECK ACCELERATOR PEDAL POSITION
SENSOR OUTPUT.
1) Measure the voltage between accelerator
pedal position sensor connector and chassis
ground.
Connector & terminal
(B315) No. 6 (+) — Chassis ground (–):
(B315) No. 3 (+) — Chassis ground (–):
Is the difference in measured
values for the main accelerator
pedal position sensor signal
and the sub accelerator pedal
position sensor signal 0 V?
Replace the accel-
erator pedal. <Ref.
to SP(w/o STI)-4,
Accelerator
Pedal.>
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and accelerator
pedal position sen-
sor connector
Short circuit to
ground in harness
between ECM con-
nector and accel-
erator pedal
position sensor
connector
3 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR
CONNECTOR.
Measure the resistance of harness between the
accelerator pedal position sensor connector
and chassis ground.
Connector & terminal
(B315) No. 5 — Chassis ground:
(B315) No. 2 — Chassis ground:
Is the resistance less than 5 Ω? Repair the poor
contact of ECM
connector.
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit of
harness between
ECM connector
and accelerator
pedal position sen-
sor connector
Open circuit of
harness between
ECM connector
and engine ground
Poor contact of
coupling connector
15WRX_STI_US_EN.book 445 ージ 20  
EN(w/o STI)(diag)-446
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FX:DTC P2146 FUEL INJECTOR POWER SUPPLY A OPEN CIRCUIT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-209, DTC P2146 FUEL INJECTOR POWER SUPPLY A
OPEN CIRCUIT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and engine ground.
Connector & terminal
(B134) No. 36 (+) — Engine ground (–):
(B134) No. 48 (+) — Engine ground (–):
Is the voltage 10 V or more? Repair the poor
contact of ECM
connector.
Go to step 2.
3
4
12
9
5
7
8
6
10
12
13
11
14
16
17
15
B564
24
23
25
12 13 14
15
16
26
2221
20
19
1817
10 11
2
4
5
13
7698
F27
B: B143
1234 56789
10 11 12 13 14 15 16 17 18 19 20
F35C:
12
3
45
6789
10 11 12
12 3
4567
F36E:B144
D:
1
5
76
2
8
34
9
B143
B:
F27
7
B134
38
48
36
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
EN-10832
B564
13
11
12
9
6
B9
E7
C4
D4
F35
C:
B144
D:
F36
E:
M/B
SBF-5
ECM
FUEL INJECTOR
RELAY
BATTERY
(BROWN)
RELAY HOLDER
15WRX_STI_US_EN.book 446 ージ 20  
EN(w/o STI)(diag)-447
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
2 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR RELAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Remove the fuel injector relay.
4) Measure the resistance between fuel injec-
tor relay connector and engine ground.
Connector & terminal
(B564) No. 12 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 3. Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
relay connector.
3 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR RELAY CONNECTOR.
Measure the resistance of harness between
ECM connector and fuel injector relay connec-
tor.
Connector & terminal
(B134) No. 36 — (B564) No. 12:
(B134) No. 48 — (B564) No. 12:
(B134) No. 38 — (B564) No. 9:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit in harness
between ECM con-
nector and fuel
injector relay con-
nector.
4 CHECK INPUT VOLTAGE OF FUEL INJEC-
TOR RELAY.
Measure the voltage between fuel injector relay
connector and the engine ground.
Connector & terminal
(B564) No. 13 (+) — Engine ground (–):
(B564) No. 11 (+) — Engine ground (–):
Is the voltage 10 V or more? Replace the fuel
injector relay. <Ref.
to FU(w/o STI)-
143, Fuel Injector
Relay.>
Repair the open or
ground short circuit
of harness of
power supply cir-
cuit.
Step Check Yes No
15WRX_STI_US_EN.book 447 ージ 20  
EN(w/o STI)(diag)-448
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FY:DTC P2158 VEHICLE SPEED SENSOR "B"
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-210, DTC P2158 VEHICLE SPEED SENSOR "B", Diag-
nostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK DTC OF VDC.
Check DTC of VDC.
Is DTC of VDC displayed? Perform the diag-
nosis according to
DTC. <Ref. to
VDC(diag)-42, List
of Diagnostic Trou-
ble Code (DTC).>
Repair the poor
contact of ECM
connector.
15WRX_STI_US_EN.book 448 ージ 20  
EN(w/o STI)(diag)-449
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
FZ:DTC P2195 O2 SENSOR SIGNAL BIASED/STUCK LEAN (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-211, DTC P2195 O2 SENSOR SIGNAL BIASED/
STUCK LEAN (BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 449 ージ 20  
EN(w/o STI)(diag)-450
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FRONT OXYGEN (A/F) SENSOR
CONNECTOR AND COUPLING CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
front oxygen (A/F) sensor.
3) Measure the resistance of harness between
ECM connector and front oxygen (A/F) sensor
connector.
Connector & terminal
(E158) No. 15 — (E24) No. 1:
(E158) No. 27 — (E24) No. 4:
(E158) No. 39 — (E24) No. 5:
Is the resistance less than 1 Ω? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector
Poor contact of
coupling connector
3 CHECK FOR POOR CONTACT.
Check for poor contact of the front oxygen (A/F)
sensor connector.
Is there poor contact of front
oxygen (A/F) sensor connec-
tor?
Repair the poor
contact of front
oxygen (A/F) sen-
sor connector.
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
15WRX_STI_US_EN.book 450 ージ 20  
EN(w/o STI)(diag)-451
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GA:DTC P2196 O2 SENSOR SIGNAL BIASED/STUCK RICH (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-213, DTC P2196 O2 SENSOR SIGNAL BIASED/
STUCK RICH (BANK 1 SENSOR 1), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 451 ージ 20  
EN(w/o STI)(diag)-452
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FRONT OXYGEN (A/F) SENSOR
CONNECTOR AND COUPLING CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and chassis ground.
Connector & terminal
(E158) No. 15 — Chassis ground:
(E158) No. 27 — Chassis ground:
(E158) No. 39 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 3. Repair the short
circuit to ground in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector.
3 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Connect the connector to ECM.
2) Disconnect the connectors from front oxy-
gen (A/F) sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(E158) No. 15 (+) — Chassis ground (–):
(E158) No. 27 (+) — Chassis ground (–):
(E158) No. 39 (+) — Chassis ground (–):
Is the voltage 8 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
Repair the poor
contact of ECM
connector.
15WRX_STI_US_EN.book 452 ージ 20  
EN(w/o STI)(diag)-453
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GB:DTC P219A BANK 1 AIR-FUEL RATIO IMBALANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-215, DTC P219A BANK 1 AIR-FUEL RATIO IMBAL-
ANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Engine stalls.
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
15WRX_STI_US_EN.book 453 ージ 20  
EN(w/o STI)(diag)-454
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
1
3
2
465
E24
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E24
3
B550
418
22
B225
12
1
E3
B22
2
1
5
B22
12
3
4
5678
9
10 11 12
1413 15 16
B39
B15
C9
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10797
4B27
B134A:
E158B:
C: E159
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
FRONT OXYGEN (A/F) SENSOR
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 454 ージ 20  
EN(w/o STI)(diag)-455
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 455 ージ 20  
EN(w/o STI)(diag)-456
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FRONT OXYGEN (A/F) SENSOR
CONNECTOR AND COUPLING CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
front oxygen (A/F) sensor.
3) Measure the resistance of harness between
ECM connector and front oxygen (A/F) sensor
connector.
Connector & terminal
(E158) No. 15 — (E24) No. 1:
(E158) No. 27 — (E24) No. 4:
(E158) No. 39 — (E24) No. 5:
Is the resistance less than 1 Ω? Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector
Poor contact of
coupling connector
1
2
E6
E5
E17
E16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
2
1
E5
B11
B23
B35
EN-10794
2
1
E16
2
1
E6
2
1
E17
B47
B12
B24
B36
B48
C18
C17
C10
A35
A47
16
15
E3
B22
C26
C25
B134A:
E158B:
C: E159
ECM
FUEL INJECTOR No. 4
FUEL INJECTOR No. 3
FUEL INJECTOR No. 2
FUEL INJECTOR No. 1
(BROWN)
(GRAY)
(BLACK)
15WRX_STI_US_EN.book 456 ージ 20  
EN(w/o STI)(diag)-457
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
3 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(E158) No. 15 — Chassis ground:
(E158) No. 27 — Chassis ground:
(E158) No. 39 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair the short
circuit to ground in
harness between
ECM connector
and front oxygen
(A/F) sensor con-
nector.
4 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between front oxygen
(A/F) sensor connector and chassis ground.
Connector & terminal
(E24) No. 1 (+) — Chassis ground (–):
(E24) No. 4 (+) — Chassis ground (–):
(E24) No. 5 (+) — Chassis ground (–):
Is the voltage 8 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and front
oxygen (A/F) sen-
sor connector.
Go to step 5.
5 CHECK EXHAUST SYSTEM. Are there holes or loose bolts
on exhaust system?
Repair the exhaust
system.
Go to step 6.
6 CHECK AIR INTAKE SYSTEM. Are there holes, loose bolts or
disconnection of hose on air
intake system?
Repair the air
intake system.
Go to step 7.
7 CHECK FUEL PRESSURE.
WARNING:
Place “NO OPEN FLAMES” signs near the
working area.
CAUTION:
Be careful not to spill fuel.
1) Connect the front oxygen (A/F) sensor con-
nector.
2) Measure the fuel pressure. <Ref. to ME(w/o
STI)-31, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
Is the measured value 328 —
358 kPa (3.3 — 3.7 kgf/cm
2
, 48
— 52 psi)?
Go to step 8. Check the fuel
pump and fuel
delivery line. <Ref.
to FU(w/o STI)-
172, INSPEC-
TION, Fuel
Pump.> <Ref. to
FU(w/o STI)-201,
INSPECTION,
Fuel Delivery and
Evaporation
Lines.>
8 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm up completely.
2) Read the value of «Coolant Temp.» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Coolant Temp
75°C (167°F) or more?
Go to step 9. Replace the
engine coolant
temperature sen-
sor. <Ref. to FU(w/
o STI)-93, Engine
Coolant Tempera-
ture Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 457 ージ 20  
EN(w/o STI)(diag)-458
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
9 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Read the value of «Mass Air Flow» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Mass Air
Flow» 2.0 — 5.0 g/s (0.26 —
0.66 lb/m)?
Go to step 10. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(w/o STI)-118,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
10 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For CVT models, set the select lever to “P”
range or “N” range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Open the front hood.
6) Measure the ambient temperature.
7) Read the value of «IAT Sensor #11» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Subtract ambient temperature
value from the value of «IAT
Sensor #11». Is the obtained
value –10 — 50°C (–18 —
90°F)?
Go to step 11. Check the mass air
flow and intake air
temperature sen-
sor. <Ref. to FU(w/
o STI)-118, Mass
Air Flow and Intake
Air Temperature
Sensor.>
Step Check Yes No
15WRX_STI_US_EN.book 458 ージ 20  
EN(w/o STI)(diag)-459
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
11 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
keep the engine speed at 3,000 rpm. (2 minutes
maximum)
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» 0.490 V or more?
Go to step 12. Go to step 13.
12 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
rapidly reduce the engine speed from 3,000
rpm.
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» 0.250 V or less?
Go to step 14. Go to step 13.
13 CHECK REAR OXYGEN SENSOR CONNEC-
TOR AND COUPLING CONNECTOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 15.
14 CHECK FRONT OXYGEN (A/F) SENSOR US-
ING REAR OXYGEN SENSOR SIGNAL.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), then
keep the engine idling for 5 minutes or more.
2) Read the value of «Oxygen sensor #12»
using the Subaru Select Monitor or a general
scan tool.
NOTE:
Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(w/o STI)(diag)-37, Subaru Select Moni-
tor.>
General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Oxygen sensor
#12» kept at 0.250 V or less for
5 minutes or more?
Replace the front
oxygen (A/F) sen-
sor. <Ref. to FU(w/
o STI)-126, Front
Oxygen (A/F) Sen-
sor.>
Go to step 15.
Step Check Yes No
15WRX_STI_US_EN.book 459 ージ 20  
EN(w/o STI)(diag)-460
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
15 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 42 — (E25) No. 3:
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 16. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and rear oxygen
sensor connector
Poor contact of
coupling connector
16 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between rear oxygen
sensor connector and chassis ground.
Connector & terminal
(E25) No. 4 (+) — Chassis ground (–):
Is the voltage 0.2 — 0.5 V? Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
Go to step 17.
17 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel injector
on faulty cylinders.
3) Measure the resistance between fuel injec-
tor connector and engine ground on faulty cylin-
ders.
Connector & terminal
#1 (E5) No. 1 — Engine ground:
#1 (E5) No. 2 — Engine ground:
#2 (E16) No. 1 — Engine ground:
#2 (E16) No. 2 — Engine ground:
#3 (E6) No. 1 — Engine ground:
#3 (E6) No. 2 — Engine ground:
#4 (E17) No. 1 — Engine ground:
#4 (E17) No. 2 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 18. Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.
18 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance of harness between
ECM and fuel injector connector on faulty cylin-
ders.
Connector & terminal
#1 (E158) No. 12 — (E5) No. 1:
#1 (E158) No. 11 — (E5) No. 2:
#2 (E158) No. 24 — (E16) No. 1:
#2 (E158) No. 23 — (E16) No. 2:
#3 (E158) No. 36 — (E6) No. 1:
#3 (E158) No. 35 — (E6) No. 2:
#4 (E158) No. 48 — (E17) No. 1:
#4 (E158) No. 47 — (E17) No. 2:
Is the resistance less than 1 Ω? Go to step 19. Repair the open
circuit of the har-
ness between the
ECM connector
and fuel injector
connector.
19 CHECK FUEL INJECTOR.
Check the fuel injector on faulty cylinder. <Ref.
to FU(w/o STI)-70, INSPECTION, Fuel Injec-
tor.>
Are fuel injectors OK? Go to step 20. Replace the faulty
fuel injector. <Ref.
to FU(w/o STI)-51,
Fuel Injector.>
Step Check Yes No
15WRX_STI_US_EN.book 460 ージ 20  
EN(w/o STI)(diag)-461
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
20 CHECK INSTALLATION CONDITION OF
CAMSHAFT POSITION SENSOR/CRANK-
SHAFT POSITION SENSOR.
Is the camshaft position sensor
or crankshaft position sensor
loosely installed?
Tighten the cam-
shaft position sen-
sor or crankshaft
position sensor.
<Ref. to FU(w/o
STI)-104, INSTAL-
LATION, Cam-
shaft Position
Sensor.> <Ref. to
FU(w/o STI)-99,
INSTALLATION,
Crankshaft Posi-
tion Sensor.>
Go to step 21.
21 CHECK CRANKSHAFT POSITION SENSOR
PLATE.
Is the crankshaft position sen-
sor plate rusted or does it have
broken teeth?
Replace the crank-
shaft position sen-
sor plate. <Ref. to
ME(w/o STI)-260,
Cylinder Block.>
Go to step 22.
22 CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Turn the crankshaft using ST, and align the
alignment mark on crank sprocket with align-
ment mark on cylinder block.
ST 18252AA000 CRANKSHAFT
SOCKET
Is the timing chain dislocated
from its proper position?
Correct the instal-
lation condition of
timing chain. <Ref.
to ME(w/o STI)-
116, Timing Chain
Assembly.>
Go to step 23.
23 CHECK FUEL LEVEL. Is the fuel meter indication
higher than the “Lower” level?
Go to step 24. Refill the fuel so
that the fuel meter
indication is higher
than the “Lower”
level, and proceed
to the next step. Go
to step 24.
24 CHECK STATUS OF MALFUNCTION INDI-
CATOR LIGHT.
1) Clear the memory using the Subaru Select
Monitor or general scan tool. <Ref. to EN(w/o
STI)(diag)-61, Clear Memory Mode.>
2) Start the engine, and drive the vehicle 10
minutes or more.
Does the malfunction indicator
light illuminate or blink?
Go to step 26. Go to step 25.
25 CHECK CAUSE OF MISFIRE. Was the cause of misfire identi-
fied when the engine is run-
ning?
Finish diagnostics
operation, if the
engine has no
abnormality.
Repair the poor
contact of connec-
tor.
NOTE:
In this case, repair
the following item:
Poor contact of
ignition coil con-
nector
Poor contact of
fuel injector con-
nector on faulty
cylinders
Poor contact of
ECM connector
Poor contact of
coupling connector
Step Check Yes No
15WRX_STI_US_EN.book 461 ージ 20  
EN(w/o STI)(diag)-462
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
26 CHECK AIR INTAKE SYSTEM. Is there any fault in air intake
system?
Repair the air
intake system.
NOTE:
Check the follow-
ing items.
Are there air
leaks or air suction
caused by loose or
dislocated nuts
and bolts?
Are there cracks
or any disconnec-
tion of hoses?
Go to step 27.
27 CHECK MISFIRE SYMPTOM.
1) Turn the ignition switch to ON.
2) Check for DTC. <Ref. to EN(w/o STI)(diag)-
46, Read Diagnostic Trouble Code (DTC).>
Does the Subaru Select Moni-
tor or general scan tool indicate
only one DTC?
Go to step 30. Go to step 28.
28 CHECK DTC. Is DTC P0301 and P0303 dis-
played on the Subaru Select
Monitor or general scan tool?
Go to step 31. Go to step 29.
29 CHECK DTC. Is DTC P0302 and P0304 dis-
played on the Subaru Select
Monitor or general scan tool?
Go to step 32. Go to step 33.
30 ONLY ONE CYLINDER. Is there any fault in the cylin-
der?
Repair or replace
faulty parts.
NOTE:
Check the follow-
ing items.
Spark plug
Ignition coil
Fuel injector
Compression ra-
tio
Go to DTC P0171.
<Ref. to EN(w/o
STI)(diag)-185,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
31 GROUP OF #1 AND #3 CYLINDERS. Are there any faults in #1 and
#3 cylinders?
Repair or replace
faulty parts.
NOTE:
Check the follow-
ing items.
Spark plug
Ignition coil
Fuel injector
Compression ra-
tio
Skipping timing
chain teeth
Go to DTC P0171.
<Ref. to EN(w/o
STI)(diag)-185,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
32 GROUP OF #2 AND #4 CYLINDERS. Are there any faults in #2 and
#4 cylinders?
Repair or replace
faulty parts.
NOTE:
Check the follow-
ing items.
Spark plug
Ignition coil
Fuel injector
Compression ra-
tio
Skipping timing
chain teeth
Go to DTC P0171.
<Ref. to EN(w/o
STI)(diag)-185,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
Step Check Yes No
15WRX_STI_US_EN.book 462 ージ 20  
EN(w/o STI)(diag)-463
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
33 CYLINDER AT RANDOM. Is the engine idle rough? Go to DTC P0171.
<Ref. to EN(w/o
STI)(diag)-185,
DTC P0171 SYS-
TEM TOO LEAN
(BANK 1), Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC).>
Repair or replace
faulty parts.
NOTE:
Check the follow-
ing items.
Spark plug
Ignition coil
Fuel injector
Compression ra-
tio
Step Check Yes No
15WRX_STI_US_EN.book 463 ージ 20  
EN(w/o STI)(diag)-464
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GC:DTC P2227 BAROMETRIC PRESSURE CIRCUIT RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-220, DTC P2227 BAROMETRIC PRESSURE CIRCUIT
RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
GD:DTC P2228 BAROMETRIC PRESSURE CIRCUIT LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-221, DTC P2228 BAROMETRIC PRESSURE CIRCUIT
LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(w/o STI)(diag)-
85, List of Diagnos-
tic Trouble Code
(DTC).>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
NOTE:
The barometric
pressure sensor is
built into the ECM.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(w/o STI)(diag)-
85, List of Diagnos-
tic Trouble Code
(DTC).>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
NOTE:
The barometric
pressure sensor is
built into the ECM.
15WRX_STI_US_EN.book 464 ージ 20  
EN(w/o STI)(diag)-465
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GE:DTC P2229 BAROMETRIC PRESSURE CIRCUIT HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-222, DTC P2229 BAROMETRIC PRESSURE CIRCUIT
HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(w/o STI)(diag)-
85, List of Diagnos-
tic Trouble Code
(DTC).>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
NOTE:
The barometric
pressure sensor is
built into the ECM.
15WRX_STI_US_EN.book 465 ージ 20  
EN(w/o STI)(diag)-466
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GF:DTC P2270 O2 SENSOR SIGNAL BIASED/STUCK LEAN (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-223, DTC P2270 O2 SENSOR SIGNAL BIASED/
STUCK LEAN (BANK 1 SENSOR 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 466 ージ 20  
EN(w/o STI)(diag)-467
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK REAR OXYGEN SENSOR CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 42 — (E25) No. 3:
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit of harness
between ECM con-
nector and rear
oxygen sensor
connector.
3 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between rear oxygen
sensor connector and engine ground.
Connector & terminal
(E25) No. 3 (+) — Engine ground (–):
Is the voltage 0.15 V or more? Repair the short
circuit to power in
the harness
between ECM con-
nector and rear
oxygen sensor
connector.
Go to step 4.
4 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items.
Looseness and improper fitting of exhaust
system parts
Damage (crack, hole etc.) of parts
Damage (crack, hole etc.) between front oxy-
gen (A/F) sensor and rear oxygen sensor
Is there any fault in exhaust
system?
Repair or replace
faulty parts.
Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
15WRX_STI_US_EN.book 467 ージ 20  
EN(w/o STI)(diag)-468
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GG:DTC P2271 O2 SENSOR SIGNAL BIASED/STUCK RICH (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-225, DTC P2271 O2 SENSOR SIGNAL BIASED/
STUCK RICH (BANK 1 SENSOR 2), Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
B:
E158
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
E25
1
B550
418
22
B225
12
1
E3
B22
2
3
4
B22
12
3
4
5678
9
10 11 12
1413 15 16
B16
B42
C3
B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10798
B134A:
E158B:
C: E159
12
34
E25
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
SBF-5
ECM
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
A/F,
OXYGEN SENSOR
RELAY
BATTERY
FUSE HOLDER
REAR OXYGEN SENSOR
(BROWN)
(GRAY)(BLACK)
15WRX_STI_US_EN.book 468 ージ 20  
EN(w/o STI)(diag)-469
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK REAR OXYGEN SENSOR CONNEC-
TOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness between
ECM connector and rear oxygen sensor con-
nector.
Connector & terminal
(E158) No. 42 — (E25) No. 3:
(E158) No. 16 — (E25) No. 4:
Is the resistance less than 1 Ω? Go to step 3. Repair the open
circuit of harness
between ECM con-
nector and rear
oxygen sensor
connector.
3 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
Measure the resistance between the ECM con-
nector and engine ground.
Connector & terminal
(E158) No. 42 — Engine ground:
Is the resistance 1 MΩ or
more?
Go to step 4. Repair the short
circuit to ground in
harness between
ECM connector
and rear oxygen
sensor connector.
4 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items.
Looseness and improper fitting of exhaust
system parts
Damage (crack, hole etc.) of parts
Damage (crack, hole etc.) between front oxy-
gen (A/F) sensor and rear oxygen sensor
Is there any fault in exhaust
system?
Repair or replace
faulty parts.
Replace the rear
oxygen sensor.
<Ref. to FU(w/o
STI)-128, Rear
Oxygen Sensor.>
15WRX_STI_US_EN.book 469 ージ 20  
EN(w/o STI)(diag)-470
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GH:DTC P2401 EVAPORATIVE EMISSION SYSTEM LEAK DETECTION PUMP
CONTROL CIRCUIT LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-226, DTC P2401 EVAPORATIVE EMISSION SYSTEM
LEAK DETECTION PUMP CONTROL CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B97
1234 56789
10 11 12 13 14 15 16 17 18 19 20
78
5
6
34
2
1
B122
EN-10808
20
15
16
18
R1B97
19
17
*
*
B122
J/C
*
3
4
R400
1234
5678
R400
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
3
B134
5
1
6
7
8
19
27
18
15
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BROWN)
VACUUM
PUMP
MAIN RELAY
BATTERY
FUSE HOLDER
LEAK CHECK VALVE ASSY
SWITCHING
VALVE
PRESSURE
SENSOR
: TERMINAL No. OPTIONAL ARRANGEMENT
15WRX_STI_US_EN.book 470 ージ 20  
EN(w/o STI)(diag)-471
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B134) No. 3 (+) — Chassis ground (–):
Is the voltage 10 V or more? Go to step 2. Go to step 3.
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary open or
short circuit of har-
ness or temporary
poor contact of
connector may be
the cause.
3 CHECK POWER SUPPLY TO LEAK CHECK
VALVE ASSEMBLY.
Measure the voltage between the leak check
valve assembly connector and engine ground.
Connector & terminal
(R400) No. 3 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the power
supply circuit.
4 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the leak check valve assembly.
3) Measure the resistance between leak check
valve assembly and chassis ground.
Connector & terminal
(R400) No. 4 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and leak check
valve assembly
connector.
5 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
Measure the resistance of harness between
ECM connector and the leak check valve
assembly connector.
Connector & terminal
(B134) No. 3 — (R400) No. 4:
Is the resistance less than 1 Ω? Go to step 6. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and the leak check
valve assembly
connector
Poor contact of
coupling connector
15WRX_STI_US_EN.book 471 ージ 20  
EN(w/o STI)(diag)-472
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK LEAK CHECK VALVE ASSEMBLY.
Check the vacuum pump of the leak check valve
assembly. <Ref. to EC(w/o STI)-70, CHECK
VACUUM PUMP, INSPECTION, Leak Check
Valve Assembly.>
Is the vacuum pump of the leak
check valve assembly OK?
Repair the poor
contact in the leak
check valve
assembly connec-
tor.
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
Step Check Yes No
15WRX_STI_US_EN.book 472 ージ 20  
EN(w/o STI)(diag)-473
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GI: DTC P2402 EVAPORATIVE EMISSION SYSTEM LEAK DETECTION PUMP
CONTROL CIRCUIT HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-227, DTC P2402 EVAPORATIVE EMISSION SYSTEM
LEAK DETECTION PUMP CONTROL CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B97
1234 56789
10 11 12 13 14 15 16 17 18 19 20
78
5
6
34
2
1
B122
EN-10808
20
15
16
18
R1B97
19
17
*
*
B122
J/C
*
3
4
R400
1234
5678
R400
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
3
B134
5
1
6
7
8
19
27
18
15
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BROWN)
VACUUM
PUMP
MAIN RELAY
BATTERY
FUSE HOLDER
LEAK CHECK VALVE ASSY
SWITCHING
VALVE
PRESSURE
SENSOR
: TERMINAL No. OPTIONAL ARRANGEMENT
15WRX_STI_US_EN.book 473 ージ 20  
EN(w/o STI)(diag)-474
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the leak
check valve assembly.
3) Turn the ignition switch to ON.
4) Measure the voltage between leak check
valve assembly and chassis ground.
Connector & terminal
(R400) No. 4 (+) — Chassis ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
harness between
ECM connector
and leak check
valve assembly
connector.
Go to step 2.
2 CHECK LEAK CHECK VALVE ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Check the vacuum pump of the leak check
valve assembly. <Ref. to EC(w/o STI)-70,
CHECK VACUUM PUMP, INSPECTION, Leak
Check Valve Assembly.>
Is the vacuum pump of the leak
check valve assembly OK?
Repair the poor
contact in the leak
check valve
assembly connec-
tor.
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
15WRX_STI_US_EN.book 474 ージ 20  
EN(w/o STI)(diag)-475
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GJ:DTC P2404 EVAPORATIVE EMISSION SYSTEM LEAK DETECTION PUMP
SENSE CIRCUIT RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-228, DTC P2404 EVAPORATIVE EMISSION SYSTEM
LEAK DETECTION PUMP SENSE CIRCUIT RANGE/PERFORMANCE, Diagnostic Trouble Code (DTC)
Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B97
1234 56789
10 11 12 13 14 15 16 17 18 19 20
78
5
6
34
2
1
B122
EN-10808
20
15
16
18
R1B97
19
17
*
*
B122
J/C
*
3
4
R400
1234
5678
R400
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
3
B134
5
1
6
7
8
19
27
18
15
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BROWN)
VACUUM
PUMP
MAIN RELAY
BATTERY
FUSE HOLDER
LEAK CHECK VALVE ASSY
SWITCHING
VALVE
PRESSURE
SENSOR
: TERMINAL No. OPTIONAL ARRANGEMENT
15WRX_STI_US_EN.book 475 ージ 20  
EN(w/o STI)(diag)-476
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
<Ref. to EN(w/o
STI)(diag)-85, List
of Diagnostic Trou-
ble Code (DTC).>
Go to step 2.
2 CHECK ELCM PUMP.
Operate the ELCM pump using the Subaru
Select Monitor.
NOTE:
For detailed procedures, refer to “System Oper-
ation Check Mode”. <Ref. to EN(w/o STI)(diag)-
62, System Operation Check Mode.>
Does the ELCM pump operate? Go to step 6. Go to step 3.
3 CHECK POWER SUPPLY OF LEAK CHECK
VALVE ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the leak
check valve assembly.
3) Turn the ignition switch to ON.
4) Measure the voltage between the leak
check valve assembly connector and chassis
ground.
Connector & terminal
(R400) No. 3 (+) — Chassis ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
the main relay and
the leak check
valve assembly
connector
Poor contact of
main relay connec-
tor
Poor contact of
coupling connector
4 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and the leak check valve
assembly connector.
Connector & terminal
(B134) No. 3 — (R400) No. 4:
Is the resistance less than 1 Ω? Go to step 5. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and the leak check
valve assembly
connector
Poor contact of
coupling connector
5 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B134) No. 3 — Chassis ground:
Is the resistance 1 MΩ or
more?
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
Repair the short
circuit to ground in
harness between
ECM connector
and leak check
valve assembly
connector.
6 CHECK ELCM SWITCHING VALVE.
Operate the ELCM switching valve using the
Subaru Select Monitor.
NOTE:
For detailed procedures, refer to “System Oper-
ation Check Mode”. <Ref. to EN(w/o STI)(diag)-
62, System Operation Check Mode.>
Does the ELCM switching valve
operate?
Go to step
10. Go to step 7.
15WRX_STI_US_EN.book 476 ージ 20  
EN(w/o STI)(diag)-477
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
7 CHECK POWER SUPPLY OF LEAK CHECK
VALVE ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the leak
check valve assembly.
3) Turn the ignition switch to ON.
4) Measure the voltage between the leak
check valve assembly connector and chassis
ground.
Connector & terminal
(R400) No. 5 (+) — Chassis ground (–):
Is the voltage 10 V or more? Go to step 8. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
the main relay and
the leak check
valve assembly
connector
Poor contact of
main relay connec-
tor
Poor contact of
coupling connector
8 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness between
ECM connector and the leak check valve
assembly connector.
Connector & terminal
(B134) No. 27 — (R400) No. 1:
Is the resistance less than 1 Ω? Go to step 9. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and the leak check
valve assembly
connector
Poor contact of
coupling connector
9 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B134) No. 27 — Chassis ground:
Is the resistance 1 MΩ or
more?
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
Repair the short
circuit to ground in
harness between
ECM connector
and leak check
valve assembly
connector.
10 CHECK EVAPORATIVE EMISSION CON-
TROL SYSTEM.
Perform drive cycle I. <Ref. to EN(w/o
STI)(diag)-56, DRIVE CYCLE I, PROCEDURE,
Drive Cycle.>
Is DTC P2404 displayed on the
display?
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector,
temporary open or
short circuit of har-
ness may be the
cause.
Step Check Yes No
15WRX_STI_US_EN.book 477 ージ 20  
EN(w/o STI)(diag)-478
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GK:DTC P2419 EVAPORATIVE EMISSION SYSTEM SWITCHING VALVE CON-
TROL CIRCUIT LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-229, DTC P2419 EVAPORATIVE EMISSION SYSTEM
SWITCHING VALVE CONTROL CIRCUIT LOW, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B97
1234 56789
10 11 12 13 14 15 16 17 18 19 20
78
5
6
34
2
1
B122
EN-10808
20
15
16
18
R1B97
19
17
*
*
B122
J/C
*
3
4
R400
1234
5678
R400
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
3
B134
5
1
6
7
8
19
27
18
15
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BROWN)
VACUUM
PUMP
MAIN RELAY
BATTERY
FUSE HOLDER
LEAK CHECK VALVE ASSY
SWITCHING
VALVE
PRESSURE
SENSOR
: TERMINAL No. OPTIONAL ARRANGEMENT
15WRX_STI_US_EN.book 478 ージ 20  
EN(w/o STI)(diag)-479
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B134) No. 27 (+) — Chassis ground (–):
Is the voltage 10 V or more? Go to step 2. Go to step 3.
2 CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector.
Is there poor contact of ECM
connector?
Repair the poor
contact of ECM
connector.
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary open or
short circuit of har-
ness or temporary
poor contact of
connector may be
the cause.
3 CHECK POWER SUPPLY TO LEAK CHECK
VALVE ASSEMBLY.
Measure the voltage between the leak check
valve assembly connector and engine ground.
Connector & terminal
(R400) No. 5 (+) — Engine ground (–):
Is the voltage 10 V or more? Go to step 4. Repair the power
supply circuit.
4 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the leak check valve assembly.
3) Measure the resistance between leak check
valve assembly and chassis ground.
Connector & terminal
(R400) No. 1 — Chassis ground:
Is the resistance 1 MΩ or
more?
Go to step 5. Repair the short
circuit to ground in
harness between
ECM connector
and leak check
valve assembly
connector.
5 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
Measure the resistance of harness between
ECM connector and the leak check valve
assembly connector.
Connector & terminal
(B134) No. 27 — (R400) No. 1:
Is the resistance less than 1 Ω? Go to step 6. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and the leak check
valve assembly
connector
Poor contact of
coupling connector
15WRX_STI_US_EN.book 479 ージ 20  
EN(w/o STI)(diag)-480
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK LEAK CHECK VALVE ASSEMBLY.
Check the switching valve of the leak check
valve assembly. <Ref. to EC(w/o STI)-68,
CHECK SWITCHING VALVE, INSPECTION,
Leak Check Valve Assembly.>
Is the switching valve of the
leak check valve assembly OK?
Repair the poor
contact in the leak
check valve
assembly connec-
tor.
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
Step Check Yes No
15WRX_STI_US_EN.book 480 ージ 20  
EN(w/o STI)(diag)-481
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GL:DTC P2420 EVAPORATIVE EMISSION SYSTEM SWITCHING VALVE CON-
TROL CIRCUIT HIGH
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-230, DTC P2420 EVAPORATIVE EMISSION SYSTEM
SWITCHING VALVE CONTROL CIRCUIT HIGH, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
B97
1234 56789
10 11 12 13 14 15 16 17 18 19 20
78
5
6
34
2
1
B122
EN-10808
20
15
16
18
R1B97
19
17
*
*
B122
J/C
*
3
4
R400
1234
5678
R400
B220
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
B550
215
01
B220
11
3
B134
5
1
6
7
8
19
27
18
15
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
ECM
SBF-7
(BROWN)
VACUUM
PUMP
MAIN RELAY
BATTERY
FUSE HOLDER
LEAK CHECK VALVE ASSY
SWITCHING
VALVE
PRESSURE
SENSOR
: TERMINAL No. OPTIONAL ARRANGEMENT
15WRX_STI_US_EN.book 481 ージ 20  
EN(w/o STI)(diag)-482
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
LEAK CHECK VALVE ASSEMBLY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the leak
check valve assembly.
3) Turn the ignition switch to ON.
4) Measure the voltage between leak check
valve assembly and chassis ground.
Connector & terminal
(R400) No. 1 (+) — Chassis ground (–):
Is the voltage 10 V or more? Repair the short
circuit to power in
harness between
ECM connector
and leak check
valve assembly
connector.
Go to step 2.
2 CHECK LEAK CHECK VALVE ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Check the switching valve of the leak check
valve assembly. <Ref. to EC(w/o STI)-68,
CHECK SWITCHING VALVE, INSPECTION,
Leak Check Valve Assembly.>
Is the switching valve of the
leak check valve assembly OK?
Repair the poor
contact in the leak
check valve
assembly connec-
tor.
Replace the leak
check valve
assembly. <Ref. to
EC(w/o STI)-54,
Leak Check Valve
Assembly.>
15WRX_STI_US_EN.book 482 ージ 20  
EN(w/o STI)(diag)-483
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GM:DTC P2530 IGNITION SWITCH RUN POSITION CIRCUIT
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-231, DTC P2530 IGNITION SWITCH RUN POSITION
CIRCUIT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
WP
OP
WP
OP
B72
B550
923
41
B225
36 37
B22
12
3
4
5678
9
10 11 12
1413 15 16
5
7
8
6
3
9
12
4
13
15
16
14
11
10
17 18
25 26
12
21
23
24
22
19 20
29
31
32
30
27 28
C:
E159
10
11 12
23 24
35 36
47 48
3
5
6
7894
12
45
4643 4441 4239 4037 38
21
2219 2017 1815 1613 14
33
3431 3229 3027 2825 26
B134A:
B550
215
B220
11
12
10
13
B134A:
E159C:
A32
A23
A38
A24
A12
B220 B225
10 11
12
13
14 15
16
18
19 21 22
20
17
24
5
3
17
9
8
6
32 33
34
35
28262423
25
27
29
30
31
36 37
38
40
41 43 44
42
39
EN-10792
WP
OP
C25
C26
16
15
E3
B22
A47
A35
C10
C17
C18
B72
7856
3412
ECM
SBF-7
SBF-6
91
2
232221 262524201918
4
13
12
17
3
16
6
15
587
14
10 11
B550
: WITHOUT PUSH BUTTON START
: WITH PUSH BUTTON START
BATTERY
MAIN
RELAY
FUSE HOLDER
M/B No. 13
F/B No. 12
(BROWN)
(GRAY)
IG RELAY 1
(PUSH BUTTON
START)
FUSE HOLDER
IGNITION
SWITCH
MAIN SBF
15WRX_STI_US_EN.book 483 ージ 20  
EN(w/o STI)(diag)-484
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1 CHECK ECM CONNECTOR.
Check the connecting condition of ECM con-
nector.
Is the ECM connector correctly
connected?
Go to step 2. Connect the ECM
connector cor-
rectly.
2 CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Connect the check board.
ST 18460AA030 CHECK BOARD
3) Measure the voltage between ECM connec-
tor and engine ground while wiggling the har-
ness between ECM connector and ignition
switch connector (for models without push but-
ton start), or between ECM connector and IG
relay 1 (push button start) connector (for mod-
els with push button start).
Connector & terminal
(B134) No. 32 (+) — Engine ground (–):
Is the voltage 8 V or more all the
time?
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, the fol-
lowing items may
be the cause of
fault.
Model without
push button start
Open or short
circuit to ground in
harness between
ECM connector
and ignition switch
connector
Poor contact of
ignition switch con-
nector
Poor contact of
ignition switch
Model with push
button start
Open circuit or
short circuit to
ground in harness
between ECM con-
nector and IG relay
1 (push button
start) connector
Poor contact in
IG relay 1 (push
button start) con-
nector
Poor contact in
IG relay 1 (push
button start)
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Model without
push button start
Open or short
circuit to ground in
harness between
ECM connector
and ignition switch
connector
Poor contact of
ignition switch con-
nector
Poor contact of
ignition switch
Faulty fuse (F/B
No. 12)
Model with push
button start
Open circuit or
short circuit to
ground in harness
between ECM con-
nector and IG relay
1 (push button
start) connector
Poor contact in
IG relay 1 (push
button start) con-
nector
Poor contact in
IG relay 1 (push
button start)
Faulty fuse (F/B
No. 12)
15WRX_STI_US_EN.book 484 ージ 20  
EN(w/o STI)(diag)-485
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GN:DTC P2610 ECM/PCM INTERNAL ENGINE OFF TIMER PERFORMANCE
DTC DETECTING CONDITION:
Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-232, DTC P2610 ECM/PCM INTERNAL ENGINE OFF
TIMER PERFORMANCE, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
GO:DTC U0073 CONTROL MODULE COMMUNICATION BUS OFF
NOTE:
For the diagnostic procedure, refer to LAN section. <Ref. to LAN(diag)-2, Basic Diagnostic Procedure.>
Step Check Yes No
1 CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed? Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(w/o STI)(diag)-
85, List of Diagnos-
tic Trouble Code
(DTC).>
Replace the ECM.
<Ref. to FU(w/o
STI)-132, Engine
Control Module
(ECM).>
NOTE:
The soak timer IC
is built into the
ECM.
15WRX_STI_US_EN.book 485 ージ 20  
EN(w/o STI)(diag)-486
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GP:DTC U0077 LIN COMMUNICATION BUS "ECM/PCM" OFF
DTC DETECTING CONDITION:
Immediately at fault recognition
GENERAL DESCRIPTION <Ref. to GD(w/o STI)-241, DTC U0077 LIN COMMUNICATION BUS "ECM/
PCM" OFF, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(w/o STI)(diag)-61,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(w/o STI)(diag)-47, PROCE-
DURE, Inspection Mode.>.
WIRING DIAGRAM:
Engine Electrical System ENGINE TYPE FA (WITHOUT PUSH BUTTON START) <Ref. to WI-162, EN-
GINE TYPE FA (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE FA (WITH PUSH BUTTON START) <Ref. to WI-180, ENGINE
TYPE FA (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Step Check Yes No
1 CHECK DTC.
Check for DTC. <Ref. to EN(w/o STI)(diag)-46,
Read Diagnostic Trouble Code (DTC).>
Is U0077 displayed in «Present
fault»?
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
2 CHECK ECM CONNECTOR.
Check the connecting condition of ECM con-
nector.
Is the ECM connector correctly
connected?
Go to step 3. Connect the ECM
connector cor-
rectly.
12
B9
B22
12
3
4
5678
9
10 11 12
1413 15 16
7
9
10
8
5
23
11 12
6
19
21
22
20
17
24
35 36
47 48
18
31
33
34
32
29 30
43
45
46
44
41 42
3
4
12
15
16
13 14
27
28
25 26
39
40
37 38
E158
10
E3
B22
B9
3
E158
1
2
EN-10819
ECM
BATTERY SENSOR
BATTERY
M/B No. 13
(BLACK)
15WRX_STI_US_EN.book 486 ージ 20  
EN(w/o STI)(diag)-487
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
3 CHECK HARNESS BETWEEN BATTERY
AND BATTERY SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the ground terminal from battery
sensor. <Ref. to NT-5, BATTERY, NOTE, Note.>
3) Disconnect the connector from battery sen-
sor.
4) Disconnect the positive terminal of battery.
5) Measure the resistance of the harness
between battery positive cable terminal and
battery sensor connector.
Connector & terminal
Positive cable terminal — (B9) No. 1:
Is the resistance less than 1 Ω? Go to step 4. Repair the open
circuit in harness
between battery
positive cable ter-
minal and battery
sensor connector.
4 CHECK HARNESS BETWEEN ECM AND
BATTERY SENSOR CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness between
ECM connector and battery sensor connector.
Connector & terminal
(E158) No. 3 — (B9) No. 2:
Is the resistance less than 1 Ω? Repair the poor
contact of ECM
connector or bat-
tery sensor con-
nector.
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
Open circuit in
harness between
ECM connector
and battery sensor
connector
Poor contact of
coupling connector
Step Check Yes No
15WRX_STI_US_EN.book 487 ージ 20  
EN(w/o STI)(diag)-488
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
GQ:DTC U0101 LOST COMMUNICATION WITH TCM
NOTE:
For the diagnostic procedure, refer to LAN section. <Ref. to LAN(diag)-2, Basic Diagnostic Procedure.>
GR:DTC U0122 LOST COMMUNICATION WITH VEHICLE DYNAMICS CONTROL
MODULE
NOTE:
For the diagnostic procedure, refer to LAN section. <Ref. to LAN(diag)-2, Basic Diagnostic Procedure.>
GS:DTC U0155 LOST COMMUNICATION WITH INSTRUMENT PANEL CLUSTER
(IPC) CONTROL MODULE
NOTE:
For the diagnostic procedure, refer to LAN section. <Ref. to LAN(diag)-2, Basic Diagnostic Procedure.>
GT:DTC U0402 INVALID DATA RECEIVED FROM TCM
NOTE:
For the diagnostic procedure, refer to LAN section. <Ref. to LAN(diag)-2, Basic Diagnostic Procedure.>
GU:DTC U0416 INVALID DATA RECEIVED FROM VEHICLE DYNAMICS CON-
TROL MODULE
NOTE:
For the diagnostic procedure, refer to LAN section. <Ref. to LAN(diag)-2, Basic Diagnostic Procedure.>
GV:DTC U0423 INVALID DATA RECEIVED FROM INSTRUMENT PANEL CLUS-
TER CONTROL MODULE
NOTE:
For the diagnostic procedure, refer to LAN section. <Ref. to LAN(diag)-2, Basic Diagnostic Procedure.>
GW:DTC U1712 LOST LIN COMMUNICATION WITH BATTERY "1" MONITOR
MODULE
NOTE:
For the diagnostic procedure, refer to DTC U0077. <Ref. to EN(w/o STI)(diag)-486, DTC U0077 LIN COM-
MUNICATION BUS "ECM/PCM" OFF, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
15WRX_STI_US_EN.book 488 ージ 20